Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull more vfs updates from Al Viro:
 "In this pile:

   - autofs-namespace series
   - dedupe stuff
   - more struct path constification"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
  ocfs2: implement the VFS clone_range, copy_range, and dedupe_range features
  ocfs2: charge quota for reflinked blocks
  ocfs2: fix bad pointer cast
  ocfs2: always unlock when completing dio writes
  ocfs2: don't eat io errors during _dio_end_io_write
  ocfs2: budget for extent tree splits when adding refcount flag
  ocfs2: prohibit refcounted swapfiles
  ocfs2: add newlines to some error messages
  ocfs2: convert inode refcount test to a helper
  simple_write_end(): don't zero in short copy into uptodate
  exofs: don't mess with simple_write_{begin,end}
  9p: saner ->write_end() on failing copy into non-uptodate page
  fix gfs2_stuffed_write_end() on short copies
  fix ceph_write_end()
  nfs_write_end(): fix handling of short copies
  vfs: refactor clone/dedupe_file_range common functions
  fs: try to clone files first in vfs_copy_file_range
  vfs: misc struct path constification
  namespace.c: constify struct path passed to a bunch of primitives
  quota: constify struct path in quota_on
  ...

45 files changed, 978 insertions, 468 deletions

diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
index 5ca1fb0043f6..adaf6f6dd858 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -310,18 +310,10 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 
 	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
 
-	if (unlikely(copied < len)) {
-		/*
-		 * zero out the rest of the area
-		 */
-		unsigned from = pos & (PAGE_SIZE - 1);
-
-		zero_user(page, from + copied, len - copied);
-		flush_dcache_page(page);
+	if (unlikely(copied < len && !PageUptodate(page))) {
+		copied = 0;
+		goto out;
 	}
-
-	if (!PageUptodate(page))
-		SetPageUptodate(page);
 	/*
 	 * No need to use i_size_read() here, the i_size
 	 * cannot change under us because we hold the i_mutex.
@@ -331,6 +323,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping,
 		i_size_write(inode, last_pos);
 	}
 	set_page_dirty(page);
+out:
 	unlock_page(page);
 	put_page(page);
 
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index a1fba4285277..c885daae68c8 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -145,7 +145,7 @@ void autofs4_free_ino(struct autofs_info *);
 
 /* Expiration */
 int is_autofs4_dentry(struct dentry *);
-int autofs4_expire_wait(struct dentry *dentry, int rcu_walk);
+int autofs4_expire_wait(const struct path *path, int rcu_walk);
 int autofs4_expire_run(struct super_block *, struct vfsmount *,
 		       struct autofs_sb_info *,
 		       struct autofs_packet_expire __user *);
@@ -217,7 +217,8 @@ static inline int autofs_prepare_pipe(struct file *pipe)
 
 /* Queue management functions */
 
-int autofs4_wait(struct autofs_sb_info *, struct dentry *, enum autofs_notify);
+int autofs4_wait(struct autofs_sb_info *,
+		 const struct path *, enum autofs_notify);
 int autofs4_wait_release(struct autofs_sb_info *, autofs_wqt_t, int);
 void autofs4_catatonic_mode(struct autofs_sb_info *);
 
diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
index fc09eb77ddf3..6f48d670c941 100644
--- a/fs/autofs4/dev-ioctl.c
+++ b/fs/autofs4/dev-ioctl.c
@@ -204,7 +204,7 @@ static int autofs_dev_ioctl_protosubver(struct file *fp,
 /* Find the topmost mount satisfying test() */
 static int find_autofs_mount(const char *pathname,
 			     struct path *res,
-			     int test(struct path *path, void *data),
+			     int test(const struct path *path, void *data),
 			     void *data)
 {
 	struct path path;
@@ -230,12 +230,12 @@ static int find_autofs_mount(const char *pathname,
 	return err;
 }
 
-static int test_by_dev(struct path *path, void *p)
+static int test_by_dev(const struct path *path, void *p)
 {
 	return path->dentry->d_sb->s_dev == *(dev_t *)p;
 }
 
-static int test_by_type(struct path *path, void *p)
+static int test_by_type(const struct path *path, void *p)
 {
 	struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 
@@ -468,7 +468,7 @@ static int autofs_dev_ioctl_requester(struct file *fp,
 	ino = autofs4_dentry_ino(path.dentry);
 	if (ino) {
 		err = 0;
-		autofs4_expire_wait(path.dentry, 0);
+		autofs4_expire_wait(&path, 0);
 		spin_lock(&sbi->fs_lock);
 		param->requester.uid =
 			from_kuid_munged(current_user_ns(), ino->uid);
@@ -575,7 +575,7 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 
 		devid = new_encode_dev(dev);
 
-		err = have_submounts(path.dentry);
+		err = path_has_submounts(&path);
 
 		if (follow_down_one(&path))
 			magic = path.dentry->d_sb->s_magic;
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index d8e6d421c27f..57725d4a8c59 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -310,26 +310,29 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
 	now = jiffies;
 	timeout = sbi->exp_timeout;
 
-	spin_lock(&sbi->fs_lock);
-	ino = autofs4_dentry_ino(root);
-	/* No point expiring a pending mount */
-	if (ino->flags & AUTOFS_INF_PENDING)
-		goto out;
 	if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
+		spin_lock(&sbi->fs_lock);
+		ino = autofs4_dentry_ino(root);
+		/* No point expiring a pending mount */
+		if (ino->flags & AUTOFS_INF_PENDING) {
+			spin_unlock(&sbi->fs_lock);
+			goto out;
+		}
 		ino->flags |= AUTOFS_INF_WANT_EXPIRE;
 		spin_unlock(&sbi->fs_lock);
 		synchronize_rcu();
-		spin_lock(&sbi->fs_lock);
 		if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
+			spin_lock(&sbi->fs_lock);
 			ino->flags |= AUTOFS_INF_EXPIRING;
 			init_completion(&ino->expire_complete);
 			spin_unlock(&sbi->fs_lock);
 			return root;
 		}
+		spin_lock(&sbi->fs_lock);
 		ino->flags &= ~AUTOFS_INF_WANT_EXPIRE;
+		spin_unlock(&sbi->fs_lock);
 	}
 out:
-	spin_unlock(&sbi->fs_lock);
 	dput(root);
 
 	return NULL;
@@ -495,8 +498,9 @@ found:
 	return expired;
 }
 
-int autofs4_expire_wait(struct dentry *dentry, int rcu_walk)
+int autofs4_expire_wait(const struct path *path, int rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 	struct autofs_info *ino = autofs4_dentry_ino(dentry);
 	int status;
@@ -525,7 +529,7 @@ retry:
 
 		pr_debug("waiting for expire %p name=%pd\n", dentry, dentry);
 
-		status = autofs4_wait(sbi, dentry, NFY_NONE);
+		status = autofs4_wait(sbi, path, NFY_NONE);
 		wait_for_completion(&ino->expire_complete);
 
 		pr_debug("expire done status=%d\n", status);
@@ -592,11 +596,12 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
 
 	if (dentry) {
 		struct autofs_info *ino = autofs4_dentry_ino(dentry);
+		const struct path path = { .mnt = mnt, .dentry = dentry };
 
 		/* This is synchronous because it makes the daemon a
 		 * little easier
 		 */
-		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
+		ret = autofs4_wait(sbi, &path, NFY_EXPIRE);
 
 		spin_lock(&sbi->fs_lock);
 		/* avoid rapid-fire expire attempts if expiry fails */
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index a11f73174877..82e8f6edfb48 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -32,7 +32,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file);
 static struct dentry *autofs4_lookup(struct inode *,
 				     struct dentry *, unsigned int);
 static struct vfsmount *autofs4_d_automount(struct path *);
-static int autofs4_d_manage(struct dentry *, bool);
+static int autofs4_d_manage(const struct path *, bool);
 static void autofs4_dentry_release(struct dentry *);
 
 const struct file_operations autofs4_root_operations = {
@@ -123,7 +123,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 	 * it.
 	 */
 	spin_lock(&sbi->lookup_lock);
-	if (!d_mountpoint(dentry) && simple_empty(dentry)) {
+	if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {
 		spin_unlock(&sbi->lookup_lock);
 		return -ENOENT;
 	}
@@ -269,39 +269,41 @@ next:
 	return NULL;
 }
 
-static int autofs4_mount_wait(struct dentry *dentry, bool rcu_walk)
+static int autofs4_mount_wait(const struct path *path, bool rcu_walk)
 {
-	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
-	struct autofs_info *ino = autofs4_dentry_ino(dentry);
+	struct autofs_sb_info *sbi = autofs4_sbi(path->dentry->d_sb);
+	struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 	int status = 0;
 
 	if (ino->flags & AUTOFS_INF_PENDING) {
 		if (rcu_walk)
 			return -ECHILD;
-		pr_debug("waiting for mount name=%pd\n", dentry);
-		status = autofs4_wait(sbi, dentry, NFY_MOUNT);
+		pr_debug("waiting for mount name=%pd\n", path->dentry);
+		status = autofs4_wait(sbi, path, NFY_MOUNT);
 		pr_debug("mount wait done status=%d\n", status);
 	}
 	ino->last_used = jiffies;
 	return status;
 }
 
-static int do_expire_wait(struct dentry *dentry, bool rcu_walk)
+static int do_expire_wait(const struct path *path, bool rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct dentry *expiring;
 
 	expiring = autofs4_lookup_expiring(dentry, rcu_walk);
 	if (IS_ERR(expiring))
 		return PTR_ERR(expiring);
 	if (!expiring)
-		return autofs4_expire_wait(dentry, rcu_walk);
+		return autofs4_expire_wait(path, rcu_walk);
 	else {
+		const struct path this = { .mnt = path->mnt, .dentry = expiring };
 		/*
 		 * If we are racing with expire the request might not
 		 * be quite complete, but the directory has been removed
 		 * so it must have been successful, just wait for it.
 		 */
-		autofs4_expire_wait(expiring, 0);
+		autofs4_expire_wait(&this, 0);
 		autofs4_del_expiring(expiring);
 		dput(expiring);
 	}
@@ -354,7 +356,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	 * and the directory was removed, so just go ahead and try
 	 * the mount.
 	 */
-	status = do_expire_wait(dentry, 0);
+	status = do_expire_wait(path, 0);
 	if (status && status != -EAGAIN)
 		return NULL;
 
@@ -362,7 +364,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 	spin_lock(&sbi->fs_lock);
 	if (ino->flags & AUTOFS_INF_PENDING) {
 		spin_unlock(&sbi->fs_lock);
-		status = autofs4_mount_wait(dentry, 0);
+		status = autofs4_mount_wait(path, 0);
 		if (status)
 			return ERR_PTR(status);
 		goto done;
@@ -370,28 +372,28 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 
 	/*
 	 * If the dentry is a symlink it's equivalent to a directory
-	 * having d_mountpoint() true, so there's no need to call back
-	 * to the daemon.
+	 * having path_is_mountpoint() true, so there's no need to call
+	 * back to the daemon.
 	 */
 	if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
 		spin_unlock(&sbi->fs_lock);
 		goto done;
 	}
 
-	if (!d_mountpoint(dentry)) {
+	if (!path_is_mountpoint(path)) {
 		/*
 		 * It's possible that user space hasn't removed directories
 		 * after umounting a rootless multi-mount, although it
-		 * should. For v5 have_submounts() is sufficient to handle
-		 * this because the leaves of the directory tree under the
-		 * mount never trigger mounts themselves (they have an autofs
-		 * trigger mount mounted on them). But v4 pseudo direct mounts
-		 * do need the leaves to trigger mounts. In this case we
-		 * have no choice but to use the list_empty() check and
+		 * should. For v5 path_has_submounts() is sufficient to
+		 * handle this because the leaves of the directory tree under
+		 * the mount never trigger mounts themselves (they have an
+		 * autofs trigger mount mounted on them). But v4 pseudo direct
+		 * mounts do need the leaves to trigger mounts. In this case
+		 * we have no choice but to use the list_empty() check and
 		 * require user space behave.
 		 */
 		if (sbi->version > 4) {
-			if (have_submounts(dentry)) {
+			if (path_has_submounts(path)) {
 				spin_unlock(&sbi->fs_lock);
 				goto done;
 			}
@@ -403,7 +405,7 @@ static struct vfsmount *autofs4_d_automount(struct path *path)
 		}
 		ino->flags |= AUTOFS_INF_PENDING;
 		spin_unlock(&sbi->fs_lock);
-		status = autofs4_mount_wait(dentry, 0);
+		status = autofs4_mount_wait(path, 0);
 		spin_lock(&sbi->fs_lock);
 		ino->flags &= ~AUTOFS_INF_PENDING;
 		if (status) {
@@ -421,8 +423,9 @@ done:
 	return NULL;
 }
 
-static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
+static int autofs4_d_manage(const struct path *path, bool rcu_walk)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 	struct autofs_info *ino = autofs4_dentry_ino(dentry);
 	int status;
@@ -431,20 +434,20 @@ static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 
 	/* The daemon never waits. */
 	if (autofs4_oz_mode(sbi)) {
-		if (!d_mountpoint(dentry))
+		if (!path_is_mountpoint(path))
 			return -EISDIR;
 		return 0;
 	}
 
 	/* Wait for pending expires */
-	if (do_expire_wait(dentry, rcu_walk) == -ECHILD)
+	if (do_expire_wait(path, rcu_walk) == -ECHILD)
 		return -ECHILD;
 
 	/*
 	 * This dentry may be under construction so wait on mount
 	 * completion.
 	 */
-	status = autofs4_mount_wait(dentry, rcu_walk);
+	status = autofs4_mount_wait(path, rcu_walk);
 	if (status)
 		return status;
 
@@ -460,7 +463,7 @@ static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 
 		if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
 			return 0;
-		if (d_mountpoint(dentry))
+		if (path_is_mountpoint(path))
 			return 0;
 		inode = d_inode_rcu(dentry);
 		if (inode && S_ISLNK(inode->i_mode))
@@ -487,7 +490,7 @@ static int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)
 		 * we can avoid needless calls ->d_automount() and avoid
 		 * an incorrect ELOOP error return.
 		 */
-		if ((!d_mountpoint(dentry) && !simple_empty(dentry)) ||
+		if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
 		    (d_really_is_positive(dentry) && d_is_symlink(dentry)))
 			status = -EISDIR;
 	}
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index e44271dfceb6..1278335ce366 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -250,8 +250,9 @@ autofs4_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
 static int validate_request(struct autofs_wait_queue **wait,
 			    struct autofs_sb_info *sbi,
 			    const struct qstr *qstr,
-			    struct dentry *dentry, enum autofs_notify notify)
+			    const struct path *path, enum autofs_notify notify)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_wait_queue *wq;
 	struct autofs_info *ino;
 
@@ -314,6 +315,7 @@ static int validate_request(struct autofs_wait_queue **wait,
 	 */
 	if (notify == NFY_MOUNT) {
 		struct dentry *new = NULL;
+		struct path this;
 		int valid = 1;
 
 		/*
@@ -333,7 +335,9 @@ static int validate_request(struct autofs_wait_queue **wait,
 					dentry = new;
 			}
 		}
-		if (have_submounts(dentry))
+		this.mnt = path->mnt;
+		this.dentry = dentry;
+		if (path_has_submounts(&this))
 			valid = 0;
 
 		if (new)
@@ -345,8 +349,9 @@ static int validate_request(struct autofs_wait_queue **wait,
 }
 
 int autofs4_wait(struct autofs_sb_info *sbi,
-		 struct dentry *dentry, enum autofs_notify notify)
+		 const struct path *path, enum autofs_notify notify)
 {
+	struct dentry *dentry = path->dentry;
 	struct autofs_wait_queue *wq;
 	struct qstr qstr;
 	char *name;
@@ -405,7 +410,7 @@ int autofs4_wait(struct autofs_sb_info *sbi,
 		return -EINTR;
 	}
 
-	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
+	ret = validate_request(&wq, sbi, &qstr, path, notify);
 	if (ret <= 0) {
 		if (ret != -EINTR)
 			mutex_unlock(&sbi->wq_mutex);
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 50bcfb80d33a..6a823719b6c5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3232,9 +3232,6 @@ int btrfs_dirty_pages(struct inode *inode, struct page **pages,
 		      size_t num_pages, loff_t pos, size_t write_bytes,
 		      struct extent_state **cached);
 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end);
-ssize_t btrfs_copy_file_range(struct file *file_in, loff_t pos_in,
-			      struct file *file_out, loff_t pos_out,
-			      size_t len, unsigned int flags);
 int btrfs_clone_file_range(struct file *file_in, loff_t pos_in,
 			   struct file *file_out, loff_t pos_out, u64 len);
 
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 448f57d108d1..b5c5da215d05 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3033,7 +3033,6 @@ const struct file_operations btrfs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= btrfs_compat_ioctl,
 #endif
-	.copy_file_range = btrfs_copy_file_range,
 	.clone_file_range = btrfs_clone_file_range,
 	.dedupe_file_range = btrfs_dedupe_file_range,
 };
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0a6902555e65..33f967d30b2a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -834,7 +834,7 @@ static inline int btrfs_may_create(struct inode *dir, struct dentry *child)
  * sys_mkdirat and vfs_mkdir, but we only do a single component lookup
  * inside this filesystem so it's quite a bit simpler.
  */
-static noinline int btrfs_mksubvol(struct path *parent,
+static noinline int btrfs_mksubvol(const struct path *parent,
 				   char *name, int namelen,
 				   struct btrfs_root *snap_src,
 				   u64 *async_transid, bool readonly,
@@ -3987,18 +3987,6 @@ out_unlock:
 	return ret;
 }
 
-ssize_t btrfs_copy_file_range(struct file *file_in, loff_t pos_in,
-			      struct file *file_out, loff_t pos_out,
-			      size_t len, unsigned int flags)
-{
-	ssize_t ret;
-
-	ret = btrfs_clone_files(file_out, file_in, pos_in, len, pos_out);
-	if (ret == 0)
-		ret = len;
-	return ret;
-}
-
 int btrfs_clone_file_range(struct file *src_file, loff_t off,
 		struct file *dst_file, loff_t destoff, u64 len)
 {
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index a0f1e2b91c8e..9cd0c0ea7cdb 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1317,25 +1317,27 @@ static int ceph_write_end(struct file *file, struct address_space *mapping,
 			  struct page *page, void *fsdata)
 {
 	struct inode *inode = file_inode(file);
-	unsigned from = pos & (PAGE_SIZE - 1);
 	int check_cap = 0;
 
 	dout("write_end file %p inode %p page %p %d~%d (%d)\n", file,
 	     inode, page, (int)pos, (int)copied, (int)len);
 
 	/* zero the stale part of the page if we did a short copy */
-	if (copied < len)
-		zero_user_segment(page, from+copied, len);
+	if (!PageUptodate(page)) {
+		if (copied < len) {
+			copied = 0;
+			goto out;
+		}
+		SetPageUptodate(page);
+	}
 
 	/* did file size increase? */
 	if (pos+copied > i_size_read(inode))
 		check_cap = ceph_inode_set_size(inode, pos+copied);
 
-	if (!PageUptodate(page))
-		SetPageUptodate(page);
-
 	set_page_dirty(page);
 
+out:
 	unlock_page(page);
 	put_page(page);
 
diff --git a/fs/dcache.c b/fs/dcache.c
index 5c7cc953ac81..252378359a8f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1273,38 +1273,44 @@ rename_retry:
 	goto again;
 }
 
-/*
- * Search for at least 1 mount point in the dentry's subdirs.
- * We descend to the next level whenever the d_subdirs
- * list is non-empty and continue searching.
- */
+struct check_mount {
+	struct vfsmount *mnt;
+	unsigned int mounted;
+};
 
-static enum d_walk_ret check_mount(void *data, struct dentry *dentry)
+static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry)
 {
-	int *ret = data;
-	if (d_mountpoint(dentry)) {
-		*ret = 1;
+	struct check_mount *info = data;
+	struct path path = { .mnt = info->mnt, .dentry = dentry };
+
+	if (likely(!d_mountpoint(dentry)))
+		return D_WALK_CONTINUE;
+	if (__path_is_mountpoint(&path)) {
+		info->mounted = 1;
 		return D_WALK_QUIT;
 	}
 	return D_WALK_CONTINUE;
 }
 
 /**
- * have_submounts - check for mounts over a dentry
- * @parent: dentry to check.
+ * path_has_submounts - check for mounts over a dentry in the
+ *                      current namespace.
+ * @parent: path to check.
  *
  * Return true if the parent or its subdirectories contain
- * a mount point
+ * a mount point in the current namespace.
  */
-int have_submounts(struct dentry *parent)
+int path_has_submounts(const struct path *parent)
 {
-	int ret = 0;
+	struct check_mount data = { .mnt = parent->mnt, .mounted = 0 };
 
-	d_walk(parent, &ret, check_mount, NULL);
+	read_seqlock_excl(&mount_lock);
+	d_walk(parent->dentry, &data, path_check_mount, NULL);
+	read_sequnlock_excl(&mount_lock);
 
-	return ret;
+	return data.mounted;
 }
-EXPORT_SYMBOL(have_submounts);
+EXPORT_SYMBOL(path_has_submounts);
 
 /*
  * Called by mount code to set a mountpoint and check if the mountpoint is
diff --git a/fs/dcookies.c b/fs/dcookies.c
index ac44a69fbea9..a26a701ef512 100644
--- a/fs/dcookies.c
+++ b/fs/dcookies.c
@@ -90,7 +90,7 @@ static void hash_dcookie(struct dcookie_struct * dcs)
 }
 
 
-static struct dcookie_struct *alloc_dcookie(struct path *path)
+static struct dcookie_struct *alloc_dcookie(const struct path *path)
 {
 	struct dcookie_struct *dcs = kmem_cache_alloc(dcookie_cache,
 							GFP_KERNEL);
@@ -113,7 +113,7 @@ static struct dcookie_struct *alloc_dcookie(struct path *path)
 /* This is the main kernel-side routine that retrieves the cookie
  * value for a dentry/vfsmnt pair.
  */
-int get_dcookie(struct path *path, unsigned long *cookie)
+int get_dcookie(const struct path *path, unsigned long *cookie)
 {
 	int err = 0;
 	struct dcookie_struct * dcs;
diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index d8072bc074a4..0ac62811b341 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -870,46 +870,31 @@ int exofs_write_begin(struct file *file, struct address_space *mapping,
 
 	page = *pagep;
 	if (page == NULL) {
-		ret = simple_write_begin(file, mapping, pos, len, flags, pagep,
-					 fsdata);
-		if (ret) {
-			EXOFS_DBGMSG("simple_write_begin failed\n");
-			goto out;
+		page = grab_cache_page_write_begin(mapping, pos >> PAGE_SHIFT,
+						   flags);
+		if (!page) {
+			EXOFS_DBGMSG("grab_cache_page_write_begin failed\n");
+			return -ENOMEM;
 		}
-
-		page = *pagep;
+		*pagep = page;
 	}
 
 	 /* read modify write */
 	if (!PageUptodate(page) && (len != PAGE_SIZE)) {
 		loff_t i_size = i_size_read(mapping->host);
 		pgoff_t end_index = i_size >> PAGE_SHIFT;
-		size_t rlen;
 
-		if (page->index < end_index)
-			rlen = PAGE_SIZE;
-		else if (page->index == end_index)
-			rlen = i_size & ~PAGE_MASK;
-		else
-			rlen = 0;
-
-		if (!rlen) {
+		if (page->index > end_index) {
 			clear_highpage(page);
 			SetPageUptodate(page);
-			goto out;
-		}
-
-		ret = _readpage(page, true);
-		if (ret) {
-			/*SetPageError was done by _readpage. Is it ok?*/
-			unlock_page(page);
-			EXOFS_DBGMSG("__readpage failed\n");
+		} else {
+			ret = _readpage(page, true);
+			if (ret) {
+				unlock_page(page);
+				EXOFS_DBGMSG("__readpage failed\n");
+			}
 		}
 	}
-out:
-	if (unlikely(ret))
-		_write_failed(mapping->host, pos + len);
-
 	return ret;
 }
 
@@ -929,18 +914,25 @@ static int exofs_write_end(struct file *file, struct address_space *mapping,
 			struct page *page, void *fsdata)
 {
 	struct inode *inode = mapping->host;
-	/* According to comment in simple_write_end i_mutex is held */
-	loff_t i_size = inode->i_size;
-	int ret;
-
-	ret = simple_write_end(file, mapping,pos, len, copied, page, fsdata);
-	if (unlikely(ret))
-		_write_failed(inode, pos + len);
+	loff_t last_pos = pos + copied;
 
-	/* TODO: once simple_write_end marks inode dirty remove */
-	if (i_size != inode->i_size)
+	if (!PageUptodate(page)) {
+		if (copied < len) {
+			_write_failed(inode, pos + len);
+			copied = 0;
+			goto out;
+		}
+		SetPageUptodate(page);
+	}
+	if (last_pos > inode->i_size) {
+		i_size_write(inode, last_pos);
 		mark_inode_dirty(inode);
-	return ret;
+	}
+	set_page_dirty(page);
+out:
+	unlock_page(page);
+	put_page(page);
+	return copied;
 }
 
 static int exofs_releasepage(struct page *page, gfp_t gfp)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dfc8309d7755..63a6b6332682 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1205,7 +1205,7 @@ static int ext4_release_dquot(struct dquot *dquot);
 static int ext4_mark_dquot_dirty(struct dquot *dquot);
 static int ext4_write_info(struct super_block *sb, int type);
 static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-			 struct path *path);
+			 const struct path *path);
 static int ext4_quota_off(struct super_block *sb, int type);
 static int ext4_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
@@ -5293,7 +5293,7 @@ static void lockdep_set_quota_inode(struct inode *inode, int subclass)
  * Standard function to be called on quota_on
  */
 static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-			 struct path *path)
+			 const struct path *path)
 {
 	int err;
 
diff --git a/fs/file_table.c b/fs/file_table.c
index ad17e05ebf95..6d982b57de92 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -155,7 +155,7 @@ over:
  * @mode: the mode with which the new file will be opened
  * @fop: the 'struct file_operations' for the new file
  */
-struct file *alloc_file(struct path *path, fmode_t mode,
+struct file *alloc_file(const struct path *path, fmode_t mode,
 		const struct file_operations *fop)
 {
 	struct file *file;
diff --git a/fs/gfs2/aops.c b/fs/gfs2/aops.c
index 5a6f52ea2722..6b039d7ce160 100644
--- a/fs/gfs2/aops.c
+++ b/fs/gfs2/aops.c
@@ -839,12 +839,10 @@ static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
 	BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
 	kaddr = kmap_atomic(page);
 	memcpy(buf + pos, kaddr + pos, copied);
-	memset(kaddr + pos + copied, 0, len - copied);
 	flush_dcache_page(page);
 	kunmap_atomic(kaddr);
 
-	if (!PageUptodate(page))
-		SetPageUptodate(page);
+	WARN_ON(!PageUptodate(page));
 	unlock_page(page);
 	put_page(page);
 
diff --git a/fs/internal.h b/fs/internal.h
index 4fcf51766d4a..b63cf3af2dc2 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -62,7 +62,7 @@ extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 extern void *copy_mount_options(const void __user *);
 extern char *copy_mount_string(const void __user *);
 
-extern struct vfsmount *lookup_mnt(struct path *);
+extern struct vfsmount *lookup_mnt(const struct path *);
 extern int finish_automount(struct vfsmount *, struct path *);
 
 extern int sb_prepare_remount_readonly(struct super_block *);
diff --git a/fs/libfs.c b/fs/libfs.c
index 48826d4da189..76048705d922 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -465,6 +465,8 @@ EXPORT_SYMBOL(simple_write_begin);
  * is not called, so a filesystem that actually does store data in .write_inode
  * should extend on what's done here with a call to mark_inode_dirty() in the
  * case that i_size has changed.
+ *
+ * Use *ONLY* with simple_readpage()
  */
 int simple_write_end(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned copied,
@@ -474,14 +476,14 @@ int simple_write_end(struct file *file, struct address_space *mapping,
 	loff_t last_pos = pos + copied;
 
 	/* zero the stale part of the page if we did a short copy */
-	if (copied < len) {
-		unsigned from = pos & (PAGE_SIZE - 1);
-
-		zero_user(page, from + copied, len - copied);
-	}
+	if (!PageUptodate(page)) {
+		if (copied < len) {
+			unsigned from = pos & (PAGE_SIZE - 1);
 
-	if (!PageUptodate(page))
+			zero_user(page, from + copied, len - copied);
+		}
 		SetPageUptodate(page);
+	}
 	/*
 	 * No need to use i_size_read() here, the i_size
 	 * cannot change under us because we hold the i_mutex.
diff --git a/fs/mount.h b/fs/mount.h
index d2e25d7b64b3..2c856fc47ae3 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -94,6 +94,12 @@ extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);
 extern int __legitimize_mnt(struct vfsmount *, unsigned);
 extern bool legitimize_mnt(struct vfsmount *, unsigned);
 
+static inline bool __path_is_mountpoint(const struct path *path)
+{
+	struct mount *m = __lookup_mnt(path->mnt, path->dentry);
+	return m && likely(!(m->mnt.mnt_flags & MNT_SYNC_UMOUNT));
+}
+
 extern void __detach_mounts(struct dentry *dentry);
 
 static inline void detach_mounts(struct dentry *dentry)
diff --git a/fs/namei.c b/fs/namei.c
index 2b55ea142273..1c372debcbbe 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1200,7 +1200,7 @@ static int follow_managed(struct path *path, struct nameidata *nd)
 		if (managed & DCACHE_MANAGE_TRANSIT) {
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
-			ret = path->dentry->d_op->d_manage(path->dentry, false);
+			ret = path->dentry->d_op->d_manage(path, false);
 			if (ret < 0)
 				break;
 		}
@@ -1263,10 +1263,10 @@ int follow_down_one(struct path *path)
 }
 EXPORT_SYMBOL(follow_down_one);
 
-static inline int managed_dentry_rcu(struct dentry *dentry)
+static inline int managed_dentry_rcu(const struct path *path)
 {
-	return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
-		dentry->d_op->d_manage(dentry, true) : 0;
+	return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
+		path->dentry->d_op->d_manage(path, true) : 0;
 }
 
 /*
@@ -1282,7 +1282,7 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
 		 * Don't forget we might have a non-mountpoint managed dentry
 		 * that wants to block transit.
 		 */
-		switch (managed_dentry_rcu(path->dentry)) {
+		switch (managed_dentry_rcu(path)) {
 		case -ECHILD:
 		default:
 			return false;
@@ -1392,8 +1392,7 @@ int follow_down(struct path *path)
 		if (managed & DCACHE_MANAGE_TRANSIT) {
 			BUG_ON(!path->dentry->d_op);
 			BUG_ON(!path->dentry->d_op->d_manage);
-			ret = path->dentry->d_op->d_manage(
-				path->dentry, false);
+			ret = path->dentry->d_op->d_manage(path, false);
 			if (ret < 0)
 				return ret == -EISDIR ? 0 : ret;
 		}
@@ -2863,7 +2862,7 @@ bool may_open_dev(const struct path *path)
 		!(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
 }
 
-static int may_open(struct path *path, int acc_mode, int flag)
+static int may_open(const struct path *path, int acc_mode, int flag)
 {
 	struct dentry *dentry = path->dentry;
 	struct inode *inode = dentry->d_inode;
@@ -2913,7 +2912,7 @@ static int may_open(struct path *path, int acc_mode, int flag)
 
 static int handle_truncate(struct file *filp)
 {
-	struct path *path = &filp->f_path;
+	const struct path *path = &filp->f_path;
 	struct inode *inode = path->dentry->d_inode;
 	int error = get_write_access(inode);
 	if (error)
diff --git a/fs/namespace.c b/fs/namespace.c
index e6c234b1a645..f7e28f8ea04d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -678,7 +678,7 @@ out:
  *
  * lookup_mnt takes a reference to the found vfsmount.
  */
-struct vfsmount *lookup_mnt(struct path *path)
+struct vfsmount *lookup_mnt(const struct path *path)
 {
 	struct mount *child_mnt;
 	struct vfsmount *m;
@@ -1159,7 +1159,36 @@ struct vfsmount *mntget(struct vfsmount *mnt)
 }
 EXPORT_SYMBOL(mntget);
 
-struct vfsmount *mnt_clone_internal(struct path *path)
+/* path_is_mountpoint() - Check if path is a mount in the current
+ *                          namespace.
+ *
+ *  d_mountpoint() can only be used reliably to establish if a dentry is
+ *  not mounted in any namespace and that common case is handled inline.
+ *  d_mountpoint() isn't aware of the possibility there may be multiple
+ *  mounts using a given dentry in a different namespace. This function
+ *  checks if the passed in path is a mountpoint rather than the dentry
+ *  alone.
+ */
+bool path_is_mountpoint(const struct path *path)
+{
+	unsigned seq;
+	bool res;
+
+	if (!d_mountpoint(path->dentry))
+		return false;
+
+	rcu_read_lock();
+	do {
+		seq = read_seqbegin(&mount_lock);
+		res = __path_is_mountpoint(path);
+	} while (read_seqretry(&mount_lock, seq));
+	rcu_read_unlock();
+
+	return res;
+}
+EXPORT_SYMBOL(path_is_mountpoint);
+
+struct vfsmount *mnt_clone_internal(const struct path *path)
 {
 	struct mount *p;
 	p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE);
@@ -1758,7 +1787,7 @@ out:
 
 /* Caller should check returned pointer for errors */
 
-struct vfsmount *collect_mounts(struct path *path)
+struct vfsmount *collect_mounts(const struct path *path)
 {
 	struct mount *tree;
 	namespace_lock();
@@ -1791,7 +1820,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
  *
  * Release with mntput().
  */
-struct vfsmount *clone_private_mount(struct path *path)
+struct vfsmount *clone_private_mount(const struct path *path)
 {
 	struct mount *old_mnt = real_mount(path->mnt);
 	struct mount *new_mnt;
@@ -2997,7 +3026,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
 	return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
 }
 
-bool path_is_under(struct path *path1, struct path *path2)
+bool path_is_under(const struct path *path1, const struct path *path2)
 {
 	bool res;
 	read_seqlock_excl(&mount_lock);
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 64c11f399b3d..55208b9b3c11 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -377,7 +377,7 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
 	 */
 	if (!PageUptodate(page)) {
 		unsigned pglen = nfs_page_length(page);
-		unsigned end = offset + len;
+		unsigned end = offset + copied;
 
 		if (pglen == 0) {
 			zero_user_segments(page, 0, offset,
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 6faaf710e563..5a4ec309e283 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -85,7 +85,7 @@ static int dnotify_handle_event(struct fsnotify_group *group,
 				struct inode *inode,
 				struct fsnotify_mark *inode_mark,
 				struct fsnotify_mark *vfsmount_mark,
-				u32 mask, void *data, int data_type,
+				u32 mask, const void *data, int data_type,
 				const unsigned char *file_name, u32 cookie)
 {
 	struct dnotify_mark *dn_mark;
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index e0e5f7c3c99f..bbc175d4213d 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -90,10 +90,10 @@ static int fanotify_get_response(struct fsnotify_group *group,
 static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
 				       struct fsnotify_mark *vfsmnt_mark,
 				       u32 event_mask,
-				       void *data, int data_type)
+				       const void *data, int data_type)
 {
 	__u32 marks_mask, marks_ignored_mask;
-	struct path *path = data;
+	const struct path *path = data;
 
 	pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
 		 " data_type=%d\n", __func__, inode_mark, vfsmnt_mark,
@@ -140,7 +140,7 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
 }
 
 struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
-						 struct path *path)
+						 const struct path *path)
 {
 	struct fanotify_event_info *event;
 
@@ -177,7 +177,7 @@ static int fanotify_handle_event(struct fsnotify_group *group,
 				 struct inode *inode,
 				 struct fsnotify_mark *inode_mark,
 				 struct fsnotify_mark *fanotify_mark,
-				 u32 mask, void *data, int data_type,
+				 u32 mask, const void *data, int data_type,
 				 const unsigned char *file_name, u32 cookie)
 {
 	int ret = 0;
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 2a5fb14115df..4500a74f8d38 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -47,4 +47,4 @@ static inline struct fanotify_event_info *FANOTIFY_E(struct fsnotify_event *fse)
 }
 
 struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
-						 struct path *path);
+						 const struct path *path);
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index db39de2dd4cb..b41515d3f081 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -86,7 +86,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
 }
 
 /* Notify this dentry's parent about a child's events. */
-int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
+int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
 {
 	struct dentry *parent;
 	struct inode *p_inode;
@@ -125,7 +125,7 @@ EXPORT_SYMBOL_GPL(__fsnotify_parent);
 static int send_to_group(struct inode *to_tell,
 			 struct fsnotify_mark *inode_mark,
 			 struct fsnotify_mark *vfsmount_mark,
-			 __u32 mask, void *data,
+			 __u32 mask, const void *data,
 			 int data_is, u32 cookie,
 			 const unsigned char *file_name)
 {
@@ -187,7 +187,7 @@ static int send_to_group(struct inode *to_tell,
  * out to all of the registered fsnotify_group.  Those groups can then use the
  * notification event in whatever means they feel necessary.
  */
-int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
+int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	     const unsigned char *file_name, u32 cookie)
 {
 	struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
@@ -199,7 +199,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
 	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
 
 	if (data_is == FSNOTIFY_EVENT_PATH)
-		mnt = real_mount(((struct path *)data)->mnt);
+		mnt = real_mount(((const struct path *)data)->mnt);
 	else
 		mnt = NULL;
 
diff --git a/fs/notify/inotify/inotify.h b/fs/notify/inotify/inotify.h
index ed855ef6f077..a6f5907a3fee 100644
--- a/fs/notify/inotify/inotify.h
+++ b/fs/notify/inotify/inotify.h
@@ -26,7 +26,7 @@ extern int inotify_handle_event(struct fsnotify_group *group,
 				struct inode *inode,
 				struct fsnotify_mark *inode_mark,
 				struct fsnotify_mark *vfsmount_mark,
-				u32 mask, void *data, int data_type,
+				u32 mask, const void *data, int data_type,
 				const unsigned char *file_name, u32 cookie);
 
 extern const struct fsnotify_ops inotify_fsnotify_ops;
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 2cd900c2c737..19e7ec109a75 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -66,7 +66,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 			 struct inode *inode,
 			 struct fsnotify_mark *inode_mark,
 			 struct fsnotify_mark *vfsmount_mark,
-			 u32 mask, void *data, int data_type,
+			 u32 mask, const void *data, int data_type,
 			 const unsigned char *file_name, u32 cookie)
 {
 	struct inotify_inode_mark *i_mark;
@@ -80,7 +80,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 
 	if ((inode_mark->mask & FS_EXCL_UNLINK) &&
 	    (data_type == FSNOTIFY_EVENT_PATH)) {
-		struct path *path = data;
+		const struct path *path = data;
 
 		if (d_unlinked(path->dentry))
 			return 0;
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index f72712f6c28d..d4ec0d8961a6 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -5194,7 +5194,7 @@ int ocfs2_change_extent_flag(handle_t *handle,
 	rec = &el->l_recs[index];
 	if (new_flags && (rec->e_flags & new_flags)) {
 		mlog(ML_ERROR, "Owner %llu tried to set %d flags on an "
-		     "extent that already had them",
+		     "extent that already had them\n",
 		     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
 		     new_flags);
 		goto out;
@@ -5202,7 +5202,7 @@ int ocfs2_change_extent_flag(handle_t *handle,
 
 	if (clear_flags && !(rec->e_flags & clear_flags)) {
 		mlog(ML_ERROR, "Owner %llu tried to clear %d flags on an "
-		     "extent that didn't have them",
+		     "extent that didn't have them\n",
 		     (unsigned long long)ocfs2_metadata_cache_owner(et->et_ci),
 		     clear_flags);
 		goto out;
@@ -5713,8 +5713,7 @@ int ocfs2_remove_btree_range(struct inode *inode,
 	struct ocfs2_refcount_tree *ref_tree = NULL;
 
 	if ((flags & OCFS2_EXT_REFCOUNTED) && len) {
-		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
-			 OCFS2_HAS_REFCOUNT_FL));
+		BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 		if (!refcount_tree_locked) {
 			ret = ocfs2_lock_refcount_tree(osb, refcount_loc, 1,
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 4d9c6f5ec28a..11556b7d93ec 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -464,6 +464,15 @@ static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
 	trace_ocfs2_bmap((unsigned long long)OCFS2_I(inode)->ip_blkno,
 			 (unsigned long long)block);
 
+	/*
+	 * The swap code (ab-)uses ->bmap to get a block mapping and then
+	 * bypasseѕ the file system for actual I/O.  We really can't allow
+	 * that on refcounted inodes, so we have to skip out here.  And yes,
+	 * 0 is the magic code for a bmap error..
+	 */
+	if (ocfs2_is_refcount_inode(inode))
+		return 0;
+
 	/* We don't need to lock journal system files, since they aren't
 	 * accessed concurrently from multiple nodes.
 	 */
@@ -2253,10 +2262,10 @@ out:
 	return ret;
 }
 
-static void ocfs2_dio_end_io_write(struct inode *inode,
-				   struct ocfs2_dio_write_ctxt *dwc,
-				   loff_t offset,
-				   ssize_t bytes)
+static int ocfs2_dio_end_io_write(struct inode *inode,
+				  struct ocfs2_dio_write_ctxt *dwc,
+				  loff_t offset,
+				  ssize_t bytes)
 {
 	struct ocfs2_cached_dealloc_ctxt dealloc;
 	struct ocfs2_extent_tree et;
@@ -2307,7 +2316,7 @@ static void ocfs2_dio_end_io_write(struct inode *inode,
 			mlog_errno(ret);
 	}
 
-	di = (struct ocfs2_dinode *)di_bh;
+	di = (struct ocfs2_dinode *)di_bh->b_data;
 
 	ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
 
@@ -2364,6 +2373,8 @@ out:
 	if (locked)
 		inode_unlock(inode);
 	ocfs2_dio_free_write_ctx(inode, dwc);
+
+	return ret;
 }
 
 /*
@@ -2378,21 +2389,19 @@ static int ocfs2_dio_end_io(struct kiocb *iocb,
 {
 	struct inode *inode = file_inode(iocb->ki_filp);
 	int level;
-
-	if (bytes <= 0)
-		return 0;
+	int ret = 0;
 
 	/* this io's submitter should not have unlocked this before we could */
 	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
 
-	if (private)
-		ocfs2_dio_end_io_write(inode, private, offset, bytes);
+	if (bytes > 0 && private)
+		ret = ocfs2_dio_end_io_write(inode, private, offset, bytes);
 
 	ocfs2_iocb_clear_rw_locked(iocb);
 
 	level = ocfs2_iocb_rw_locked_level(iocb);
 	ocfs2_rw_unlock(inode, level);
-	return 0;
+	return ret;
 }
 
 static ssize_t ocfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 000c234d7bbd..c4889655d32b 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1030,7 +1030,7 @@ int ocfs2_extend_no_holes(struct inode *inode, struct buffer_head *di_bh,
 	 * Only quota files call this without a bh, and they can't be
 	 * refcounted.
 	 */
-	BUG_ON(!di_bh && (oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!di_bh && ocfs2_is_refcount_inode(inode));
 	BUG_ON(!di_bh && !(oi->ip_flags & OCFS2_INODE_SYSTEM_FILE));
 
 	clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size);
@@ -1667,9 +1667,9 @@ static void ocfs2_calc_trunc_pos(struct inode *inode,
 	*done = ret;
 }
 
-static int ocfs2_remove_inode_range(struct inode *inode,
-				    struct buffer_head *di_bh, u64 byte_start,
-				    u64 byte_len)
+int ocfs2_remove_inode_range(struct inode *inode,
+			     struct buffer_head *di_bh, u64 byte_start,
+			     u64 byte_len)
 {
 	int ret = 0, flags = 0, done = 0, i;
 	u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
@@ -1719,8 +1719,7 @@ static int ocfs2_remove_inode_range(struct inode *inode,
 	 * within one cluster(means is not exactly aligned to clustersize).
 	 */
 
-	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL) {
-
+	if (ocfs2_is_refcount_inode(inode)) {
 		ret = ocfs2_cow_file_pos(inode, di_bh, byte_start);
 		if (ret) {
 			mlog_errno(ret);
@@ -2036,7 +2035,7 @@ int ocfs2_check_range_for_refcount(struct inode *inode, loff_t pos,
 	struct super_block *sb = inode->i_sb;
 
 	if (!ocfs2_refcount_tree(OCFS2_SB(inode->i_sb)) ||
-	    !(OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL) ||
+	    !ocfs2_is_refcount_inode(inode) ||
 	    OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
 		return 0;
 
@@ -2440,6 +2439,31 @@ out:
 	return offset;
 }
 
+static int ocfs2_file_clone_range(struct file *file_in,
+				  loff_t pos_in,
+				  struct file *file_out,
+				  loff_t pos_out,
+				  u64 len)
+{
+	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+					 len, false);
+}
+
+static ssize_t ocfs2_file_dedupe_range(struct file *src_file,
+				       u64 loff,
+				       u64 len,
+				       struct file *dst_file,
+				       u64 dst_loff)
+{
+	int error;
+
+	error = ocfs2_reflink_remap_range(src_file, loff, dst_file, dst_loff,
+					  len, true);
+	if (error)
+		return error;
+	return len;
+}
+
 const struct inode_operations ocfs2_file_iops = {
 	.setattr	= ocfs2_setattr,
 	.getattr	= ocfs2_getattr,
@@ -2479,6 +2503,8 @@ const struct file_operations ocfs2_fops = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
+	.clone_file_range = ocfs2_file_clone_range,
+	.dedupe_file_range = ocfs2_file_dedupe_range,
 };
 
 const struct file_operations ocfs2_dops = {
@@ -2524,6 +2550,8 @@ const struct file_operations ocfs2_fops_no_plocks = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
+	.clone_file_range = ocfs2_file_clone_range,
+	.dedupe_file_range = ocfs2_file_dedupe_range,
 };
 
 const struct file_operations ocfs2_dops_no_plocks = {
diff --git a/fs/ocfs2/file.h b/fs/ocfs2/file.h
index e8c62f22215c..897fd9a2e51d 100644
--- a/fs/ocfs2/file.h
+++ b/fs/ocfs2/file.h
@@ -82,4 +82,7 @@ int ocfs2_change_file_space(struct file *file, unsigned int cmd,
 
 int ocfs2_check_range_for_refcount(struct inode *inode, loff_t pos,
 				   size_t count);
+int ocfs2_remove_inode_range(struct inode *inode,
+			     struct buffer_head *di_bh, u64 byte_start,
+			     u64 byte_len);
 #endif /* OCFS2_FILE_H */
diff --git a/fs/ocfs2/inode.h b/fs/ocfs2/inode.h
index 5af68fcdf9d3..9b955f732bca 100644
--- a/fs/ocfs2/inode.h
+++ b/fs/ocfs2/inode.h
@@ -181,4 +181,10 @@ static inline struct ocfs2_inode_info *cache_info_to_inode(struct ocfs2_caching_
 	return container_of(ci, struct ocfs2_inode_info, ip_metadata_cache);
 }
 
+/* Does this inode have the reflink flag set? */
+static inline bool ocfs2_is_refcount_inode(struct inode *inode)
+{
+	return (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL);
+}
+
 #endif /* OCFS2_INODE_H */
diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 4e8f32eb0bdb..e52a2852d50d 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -235,10 +235,7 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
 	u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
 
 	if ((ext_flags & OCFS2_EXT_REFCOUNTED) && *len) {
-
-		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
-			 OCFS2_HAS_REFCOUNT_FL));
-
+		BUG_ON(!ocfs2_is_refcount_inode(inode));
 		BUG_ON(!context->refcount_loc);
 
 		ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
@@ -581,10 +578,7 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
 	phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
 
 	if ((ext_flags & OCFS2_EXT_REFCOUNTED) && len) {
-
-		BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
-			 OCFS2_HAS_REFCOUNT_FL));
-
+		BUG_ON(!ocfs2_is_refcount_inode(inode));
 		BUG_ON(!context->refcount_loc);
 
 		ret = ocfs2_lock_refcount_tree(osb, context->refcount_loc, 1,
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 738b4ea8e990..d171d2c53f7f 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -34,6 +34,7 @@
 #include "xattr.h"
 #include "namei.h"
 #include "ocfs2_trace.h"
+#include "file.h"
 
 #include <linux/bio.h>
 #include <linux/blkdev.h>
@@ -410,7 +411,7 @@ static int ocfs2_get_refcount_block(struct inode *inode, u64 *ref_blkno)
 		goto out;
 	}
 
-	BUG_ON(!(OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 	di = (struct ocfs2_dinode *)di_bh->b_data;
 	*ref_blkno = le64_to_cpu(di->i_refcount_loc);
@@ -569,7 +570,7 @@ static int ocfs2_create_refcount_tree(struct inode *inode,
 	u32 num_got;
 	u64 suballoc_loc, first_blkno;
 
-	BUG_ON(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL);
+	BUG_ON(ocfs2_is_refcount_inode(inode));
 
 	trace_ocfs2_create_refcount_tree(
 		(unsigned long long)OCFS2_I(inode)->ip_blkno);
@@ -707,7 +708,7 @@ static int ocfs2_set_refcount_tree(struct inode *inode,
 	struct ocfs2_refcount_block *rb;
 	struct ocfs2_refcount_tree *ref_tree;
 
-	BUG_ON(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL);
+	BUG_ON(ocfs2_is_refcount_inode(inode));
 
 	ret = ocfs2_lock_refcount_tree(osb, refcount_loc, 1,
 				       &ref_tree, &ref_root_bh);
@@ -774,7 +775,7 @@ int ocfs2_remove_refcount_tree(struct inode *inode, struct buffer_head *di_bh)
 	u64 blk = 0, bg_blkno = 0, ref_blkno = le64_to_cpu(di->i_refcount_loc);
 	u16 bit = 0;
 
-	if (!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL))
+	if (!ocfs2_is_refcount_inode(inode))
 		return 0;
 
 	BUG_ON(!ref_blkno);
@@ -2298,11 +2299,10 @@ int ocfs2_decrease_refcount(struct inode *inode,
 {
 	int ret;
 	u64 ref_blkno;
-	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 	struct buffer_head *ref_root_bh = NULL;
 	struct ocfs2_refcount_tree *tree;
 
-	BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 	ret = ocfs2_get_refcount_block(inode, &ref_blkno);
 	if (ret) {
@@ -2532,7 +2532,6 @@ int ocfs2_prepare_refcount_change_for_del(struct inode *inode,
 					  int *ref_blocks)
 {
 	int ret;
-	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 	struct buffer_head *ref_root_bh = NULL;
 	struct ocfs2_refcount_tree *tree;
 	u64 start_cpos = ocfs2_blocks_to_clusters(inode->i_sb, phys_blkno);
@@ -2543,7 +2542,7 @@ int ocfs2_prepare_refcount_change_for_del(struct inode *inode,
 		goto out;
 	}
 
-	BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 	ret = ocfs2_get_refcount_tree(OCFS2_SB(inode->i_sb),
 				      refcount_loc, &tree);
@@ -3411,14 +3410,13 @@ static int ocfs2_refcount_cow_hunk(struct inode *inode,
 {
 	int ret;
 	u32 cow_start = 0, cow_len = 0;
-	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
 	struct buffer_head *ref_root_bh = NULL;
 	struct ocfs2_refcount_tree *ref_tree;
 	struct ocfs2_cow_context *context = NULL;
 
-	BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 	ret = ocfs2_refcount_cal_cow_clusters(inode, &di->id2.i_list,
 					      cpos, write_len, max_cpos,
@@ -3628,11 +3626,10 @@ int ocfs2_refcount_cow_xattr(struct inode *inode,
 {
 	int ret;
 	struct ocfs2_xattr_value_root *xv = vb->vb_xv;
-	struct ocfs2_inode_info *oi = OCFS2_I(inode);
 	struct ocfs2_cow_context *context = NULL;
 	u32 cow_start, cow_len;
 
-	BUG_ON(!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL));
+	BUG_ON(!ocfs2_is_refcount_inode(inode));
 
 	ret = ocfs2_refcount_cal_cow_clusters(inode, &xv->xr_list,
 					      cpos, write_len, UINT_MAX,
@@ -3695,6 +3692,9 @@ int ocfs2_add_refcount_flag(struct inode *inode,
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	struct ocfs2_alloc_context *meta_ac = NULL;
 
+	/* We need to be able to handle at least an extent tree split. */
+	ref_blocks = ocfs2_extend_meta_needed(data_et->et_root_el);
+
 	ret = ocfs2_calc_refcount_meta_credits(inode->i_sb,
 					       ref_ci, ref_root_bh,
 					       p_cluster, num_clusters,
@@ -3806,7 +3806,7 @@ static int ocfs2_attach_refcount_tree(struct inode *inode,
 
 	ocfs2_init_dealloc_ctxt(&dealloc);
 
-	if (!(oi->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL)) {
+	if (!ocfs2_is_refcount_inode(inode)) {
 		ret = ocfs2_create_refcount_tree(inode, di_bh);
 		if (ret) {
 			mlog_errno(ret);
@@ -3933,6 +3933,13 @@ static int ocfs2_add_refcounted_extent(struct inode *inode,
 	ret = ocfs2_increase_refcount(handle, ref_ci, ref_root_bh,
 				      p_cluster, num_clusters,
 				      meta_ac, dealloc);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_commit;
+	}
+
+	ret = dquot_alloc_space_nodirty(inode,
+		ocfs2_clusters_to_bytes(osb->sb, num_clusters));
 	if (ret)
 		mlog_errno(ret);
 
@@ -4441,3 +4448,434 @@ out:
 
 	return error;
 }
+
+/* Update destination inode size, if necessary. */
+static int ocfs2_reflink_update_dest(struct inode *dest,
+				     struct buffer_head *d_bh,
+				     loff_t newlen)
+{
+	handle_t *handle;
+	int ret;
+
+	dest->i_blocks = ocfs2_inode_sector_count(dest);
+
+	if (newlen <= i_size_read(dest))
+		return 0;
+
+	handle = ocfs2_start_trans(OCFS2_SB(dest->i_sb),
+				   OCFS2_INODE_UPDATE_CREDITS);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		mlog_errno(ret);
+		return ret;
+	}
+
+	/* Extend i_size if needed. */
+	spin_lock(&OCFS2_I(dest)->ip_lock);
+	if (newlen > i_size_read(dest))
+		i_size_write(dest, newlen);
+	spin_unlock(&OCFS2_I(dest)->ip_lock);
+	dest->i_ctime = dest->i_mtime = current_time(dest);
+
+	ret = ocfs2_mark_inode_dirty(handle, dest, d_bh);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_commit;
+	}
+
+out_commit:
+	ocfs2_commit_trans(OCFS2_SB(dest->i_sb), handle);
+	return ret;
+}
+
+/* Remap the range pos_in:len in s_inode to pos_out:len in t_inode. */
+static int ocfs2_reflink_remap_extent(struct inode *s_inode,
+				      struct buffer_head *s_bh,
+				      loff_t pos_in,
+				      struct inode *t_inode,
+				      struct buffer_head *t_bh,
+				      loff_t pos_out,
+				      loff_t len,
+				      struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+	struct ocfs2_extent_tree s_et;
+	struct ocfs2_extent_tree t_et;
+	struct ocfs2_dinode *dis;
+	struct buffer_head *ref_root_bh = NULL;
+	struct ocfs2_refcount_tree *ref_tree;
+	struct ocfs2_super *osb;
+	loff_t pstart, plen;
+	u32 p_cluster, num_clusters, slast, spos, tpos;
+	unsigned int ext_flags;
+	int ret = 0;
+
+	osb = OCFS2_SB(s_inode->i_sb);
+	dis = (struct ocfs2_dinode *)s_bh->b_data;
+	ocfs2_init_dinode_extent_tree(&s_et, INODE_CACHE(s_inode), s_bh);
+	ocfs2_init_dinode_extent_tree(&t_et, INODE_CACHE(t_inode), t_bh);
+
+	spos = ocfs2_bytes_to_clusters(s_inode->i_sb, pos_in);
+	tpos = ocfs2_bytes_to_clusters(t_inode->i_sb, pos_out);
+	slast = ocfs2_clusters_for_bytes(s_inode->i_sb, pos_in + len);
+
+	while (spos < slast) {
+		if (fatal_signal_pending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
+
+		/* Look up the extent. */
+		ret = ocfs2_get_clusters(s_inode, spos, &p_cluster,
+					 &num_clusters, &ext_flags);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		num_clusters = min_t(u32, num_clusters, slast - spos);
+
+		/* Punch out the dest range. */
+		pstart = ocfs2_clusters_to_bytes(t_inode->i_sb, tpos);
+		plen = ocfs2_clusters_to_bytes(t_inode->i_sb, num_clusters);
+		ret = ocfs2_remove_inode_range(t_inode, t_bh, pstart, plen);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		if (p_cluster == 0)
+			goto next_loop;
+
+		/* Lock the refcount btree... */
+		ret = ocfs2_lock_refcount_tree(osb,
+					       le64_to_cpu(dis->i_refcount_loc),
+					       1, &ref_tree, &ref_root_bh);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		/* Mark s_inode's extent as refcounted. */
+		if (!(ext_flags & OCFS2_EXT_REFCOUNTED)) {
+			ret = ocfs2_add_refcount_flag(s_inode, &s_et,
+						      &ref_tree->rf_ci,
+						      ref_root_bh, spos,
+						      p_cluster, num_clusters,
+						      dealloc, NULL);
+			if (ret) {
+				mlog_errno(ret);
+				goto out_unlock_refcount;
+			}
+		}
+
+		/* Map in the new extent. */
+		ext_flags |= OCFS2_EXT_REFCOUNTED;
+		ret = ocfs2_add_refcounted_extent(t_inode, &t_et,
+						  &ref_tree->rf_ci,
+						  ref_root_bh,
+						  tpos, p_cluster,
+						  num_clusters,
+						  ext_flags,
+						  dealloc);
+		if (ret) {
+			mlog_errno(ret);
+			goto out_unlock_refcount;
+		}
+
+		ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
+		brelse(ref_root_bh);
+next_loop:
+		spos += num_clusters;
+		tpos += num_clusters;
+	}
+
+out:
+	return ret;
+out_unlock_refcount:
+	ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
+	brelse(ref_root_bh);
+	return ret;
+}
+
+/* Set up refcount tree and remap s_inode to t_inode. */
+static int ocfs2_reflink_remap_blocks(struct inode *s_inode,
+				      struct buffer_head *s_bh,
+				      loff_t pos_in,
+				      struct inode *t_inode,
+				      struct buffer_head *t_bh,
+				      loff_t pos_out,
+				      loff_t len)
+{
+	struct ocfs2_cached_dealloc_ctxt dealloc;
+	struct ocfs2_super *osb;
+	struct ocfs2_dinode *dis;
+	struct ocfs2_dinode *dit;
+	int ret;
+
+	osb = OCFS2_SB(s_inode->i_sb);
+	dis = (struct ocfs2_dinode *)s_bh->b_data;
+	dit = (struct ocfs2_dinode *)t_bh->b_data;
+	ocfs2_init_dealloc_ctxt(&dealloc);
+
+	/*
+	 * If we're reflinking the entire file and the source is inline
+	 * data, just copy the contents.
+	 */
+	if (pos_in == pos_out && pos_in == 0 && len == i_size_read(s_inode) &&
+	    i_size_read(t_inode) <= len &&
+	    (OCFS2_I(s_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)) {
+		ret = ocfs2_duplicate_inline_data(s_inode, s_bh, t_inode, t_bh);
+		if (ret)
+			mlog_errno(ret);
+		goto out;
+	}
+
+	/*
+	 * If both inodes belong to two different refcount groups then
+	 * forget it because we don't know how (or want) to go merging
+	 * refcount trees.
+	 */
+	ret = -EOPNOTSUPP;
+	if (ocfs2_is_refcount_inode(s_inode) &&
+	    ocfs2_is_refcount_inode(t_inode) &&
+	    le64_to_cpu(dis->i_refcount_loc) !=
+	    le64_to_cpu(dit->i_refcount_loc))
+		goto out;
+
+	/* Neither inode has a refcount tree.  Add one to s_inode. */
+	if (!ocfs2_is_refcount_inode(s_inode) &&
+	    !ocfs2_is_refcount_inode(t_inode)) {
+		ret = ocfs2_create_refcount_tree(s_inode, s_bh);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	/* Ensure that both inodes end up with the same refcount tree. */
+	if (!ocfs2_is_refcount_inode(s_inode)) {
+		ret = ocfs2_set_refcount_tree(s_inode, s_bh,
+					      le64_to_cpu(dit->i_refcount_loc));
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+	if (!ocfs2_is_refcount_inode(t_inode)) {
+		ret = ocfs2_set_refcount_tree(t_inode, t_bh,
+					      le64_to_cpu(dis->i_refcount_loc));
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	/* Turn off inline data in the dest file. */
+	if (OCFS2_I(t_inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+		ret = ocfs2_convert_inline_data_to_extents(t_inode, t_bh);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+	}
+
+	/* Actually remap extents now. */
+	ret = ocfs2_reflink_remap_extent(s_inode, s_bh, pos_in, t_inode, t_bh,
+					 pos_out, len, &dealloc);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+out:
+	if (ocfs2_dealloc_has_cluster(&dealloc)) {
+		ocfs2_schedule_truncate_log_flush(osb, 1);
+		ocfs2_run_deallocs(osb, &dealloc);
+	}
+
+	return ret;
+}
+
+/* Lock an inode and grab a bh pointing to the inode. */
+static int ocfs2_reflink_inodes_lock(struct inode *s_inode,
+				     struct buffer_head **bh1,
+				     struct inode *t_inode,
+				     struct buffer_head **bh2)
+{
+	struct inode *inode1;
+	struct inode *inode2;
+	struct ocfs2_inode_info *oi1;
+	struct ocfs2_inode_info *oi2;
+	bool same_inode = (s_inode == t_inode);
+	int status;
+
+	/* First grab the VFS and rw locks. */
+	lock_two_nondirectories(s_inode, t_inode);
+	inode1 = s_inode;
+	inode2 = t_inode;
+	if (inode1->i_ino > inode2->i_ino)
+		swap(inode1, inode2);
+
+	status = ocfs2_rw_lock(inode1, 1);
+	if (status) {
+		mlog_errno(status);
+		goto out_i1;
+	}
+	if (!same_inode) {
+		status = ocfs2_rw_lock(inode2, 1);
+		if (status) {
+			mlog_errno(status);
+			goto out_i2;
+		}
+	}
+
+	/* Now go for the cluster locks */
+	oi1 = OCFS2_I(inode1);
+	oi2 = OCFS2_I(inode2);
+
+	trace_ocfs2_double_lock((unsigned long long)oi1->ip_blkno,
+				(unsigned long long)oi2->ip_blkno);
+
+	if (*bh1)
+		*bh1 = NULL;
+	if (*bh2)
+		*bh2 = NULL;
+
+	/* We always want to lock the one with the lower lockid first. */
+	if (oi1->ip_blkno > oi2->ip_blkno)
+		mlog_errno(-ENOLCK);
+
+	/* lock id1 */
+	status = ocfs2_inode_lock_nested(inode1, bh1, 1, OI_LS_REFLINK_TARGET);
+	if (status < 0) {
+		if (status != -ENOENT)
+			mlog_errno(status);
+		goto out_rw2;
+	}
+
+	/* lock id2 */
+	if (!same_inode) {
+		status = ocfs2_inode_lock_nested(inode2, bh2, 1,
+						 OI_LS_REFLINK_TARGET);
+		if (status < 0) {
+			if (status != -ENOENT)
+				mlog_errno(status);
+			goto out_cl1;
+		}
+	} else
+		*bh2 = *bh1;
+
+	trace_ocfs2_double_lock_end(
+			(unsigned long long)OCFS2_I(inode1)->ip_blkno,
+			(unsigned long long)OCFS2_I(inode2)->ip_blkno);
+
+	return 0;
+
+out_cl1:
+	ocfs2_inode_unlock(inode1, 1);
+	brelse(*bh1);
+	*bh1 = NULL;
+out_rw2:
+	ocfs2_rw_unlock(inode2, 1);
+out_i2:
+	ocfs2_rw_unlock(inode1, 1);
+out_i1:
+	unlock_two_nondirectories(s_inode, t_inode);
+	return status;
+}
+
+/* Unlock both inodes and release buffers. */
+static void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
+					struct buffer_head *s_bh,
+					struct inode *t_inode,
+					struct buffer_head *t_bh)
+{
+	ocfs2_inode_unlock(s_inode, 1);
+	ocfs2_rw_unlock(s_inode, 1);
+	brelse(s_bh);
+	if (s_inode != t_inode) {
+		ocfs2_inode_unlock(t_inode, 1);
+		ocfs2_rw_unlock(t_inode, 1);
+		brelse(t_bh);
+	}
+	unlock_two_nondirectories(s_inode, t_inode);
+}
+
+/* Link a range of blocks from one file to another. */
+int ocfs2_reflink_remap_range(struct file *file_in,
+			      loff_t pos_in,
+			      struct file *file_out,
+			      loff_t pos_out,
+			      u64 len,
+			      bool is_dedupe)
+{
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+	struct ocfs2_super *osb = OCFS2_SB(inode_in->i_sb);
+	struct buffer_head *in_bh = NULL, *out_bh = NULL;
+	bool same_inode = (inode_in == inode_out);
+	ssize_t ret;
+
+	if (!ocfs2_refcount_tree(osb))
+		return -EOPNOTSUPP;
+	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
+		return -EROFS;
+
+	/* Lock both files against IO */
+	ret = ocfs2_reflink_inodes_lock(inode_in, &in_bh, inode_out, &out_bh);
+	if (ret)
+		return ret;
+
+	/* Check file eligibility and prepare for block sharing. */
+	ret = -EINVAL;
+	if ((OCFS2_I(inode_in)->ip_flags & OCFS2_INODE_SYSTEM_FILE) ||
+	    (OCFS2_I(inode_out)->ip_flags & OCFS2_INODE_SYSTEM_FILE))
+		goto out_unlock;
+
+	ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
+			&len, is_dedupe);
+	if (ret || len == 0)
+		goto out_unlock;
+
+	/* Lock out changes to the allocation maps and remap. */
+	down_write(&OCFS2_I(inode_in)->ip_alloc_sem);
+	if (!same_inode)
+		down_write_nested(&OCFS2_I(inode_out)->ip_alloc_sem,
+				  SINGLE_DEPTH_NESTING);
+
+	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
+					 out_bh, pos_out, len);
+
+	/* Zap any page cache for the destination file's range. */
+	if (!ret)
+		truncate_inode_pages_range(&inode_out->i_data, pos_out,
+					   PAGE_ALIGN(pos_out + len) - 1);
+
+	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
+	if (!same_inode)
+		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_unlock;
+	}
+
+	/*
+	 * Empty the extent map so that we may get the right extent
+	 * record from the disk.
+	 */
+	ocfs2_extent_map_trunc(inode_in, 0);
+	ocfs2_extent_map_trunc(inode_out, 0);
+
+	ret = ocfs2_reflink_update_dest(inode_out, out_bh, pos_out + len);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_unlock;
+	}
+
+	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
+	return 0;
+
+out_unlock:
+	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
+	return ret;
+}
diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index 6422bbcdb525..4af55bf4b35b 100644
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -115,4 +115,11 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 			const char __user *oldname,
 			const char __user *newname,
 			bool preserve);
+int ocfs2_reflink_remap_range(struct file *file_in,
+			      loff_t pos_in,
+			      struct file *file_out,
+			      loff_t pos_out,
+			      u64 len,
+			      bool is_dedupe);
+
 #endif /* OCFS2_REFCOUNTTREE_H */
diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index cb157a34a656..3c5384d9b3a5 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -2577,7 +2577,7 @@ int ocfs2_xattr_remove(struct inode *inode, struct buffer_head *di_bh)
 	if (!(oi->ip_dyn_features & OCFS2_HAS_XATTR_FL))
 		return 0;
 
-	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL) {
+	if (ocfs2_is_refcount_inode(inode)) {
 		ret = ocfs2_lock_refcount_tree(OCFS2_SB(inode->i_sb),
 					       le64_to_cpu(di->i_refcount_loc),
 					       1, &ref_tree, &ref_root_bh);
@@ -3608,7 +3608,7 @@ int ocfs2_xattr_set(struct inode *inode,
 	}
 
 	/* Check whether the value is refcounted and do some preparation. */
-	if (OCFS2_I(inode)->ip_dyn_features & OCFS2_HAS_REFCOUNT_FL &&
+	if (ocfs2_is_refcount_inode(inode) &&
 	    (!xis.not_found || !xbs.not_found)) {
 		ret = ocfs2_prepare_refcount_xattr(inode, di, &xi,
 						   &xis, &xbs, &ref_tree,
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 1bfac28b7e7d..8738a0d62c09 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2401,7 +2401,7 @@ int dquot_resume(struct super_block *sb, int type)
 EXPORT_SYMBOL(dquot_resume);
 
 int dquot_quota_on(struct super_block *sb, int type, int format_id,
-		   struct path *path)
+		   const struct path *path)
 {
 	int error = security_quota_on(path->dentry);
 	if (error)
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index 2d445425aad7..5acd0c4769af 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -80,7 +80,7 @@ unsigned int qtype_enforce_flag(int type)
 }
 
 static int quota_quotaon(struct super_block *sb, int type, qid_t id,
-		         struct path *path)
+		         const struct path *path)
 {
 	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_enable)
 		return -ENOSYS;
@@ -700,7 +700,7 @@ static int quota_rmxquota(struct super_block *sb, void __user *addr)
 
 /* Copy parameters and call proper function */
 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
-		       void __user *addr, struct path *path)
+		       void __user *addr, const struct path *path)
 {
 	int ret;
 
diff --git a/fs/read_write.c b/fs/read_write.c
index 53bccd1c786e..da6de12b5c46 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1540,20 +1540,37 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
 
 	sb_start_write(inode_out->i_sb);
 
-	ret = -EOPNOTSUPP;
-	if (file_out->f_op->copy_file_range)
+	/*
+	 * Try cloning first, this is supported by more file systems, and
+	 * more efficient if both clone and copy are supported (e.g. NFS).
+	 */
+	if (file_in->f_op->clone_file_range) {
+		ret = file_in->f_op->clone_file_range(file_in, pos_in,
+				file_out, pos_out, len);
+		if (ret == 0) {
+			ret = len;
+			goto done;
+		}
+	}
+
+	if (file_out->f_op->copy_file_range) {
 		ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
 						      pos_out, len, flags);
-	if (ret == -EOPNOTSUPP)
-		ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
-				len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
+		if (ret != -EOPNOTSUPP)
+			goto done;
+	}
+
+	ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
+			len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
 
+done:
 	if (ret > 0) {
 		fsnotify_access(file_in);
 		add_rchar(current, ret);
 		fsnotify_modify(file_out);
 		add_wchar(current, ret);
 	}
+
 	inc_syscr(current);
 	inc_syscw(current);
 
@@ -1648,6 +1665,114 @@ static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool write)
 	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
 }
 
+/*
+ * Check that the two inodes are eligible for cloning, the ranges make
+ * sense, and then flush all dirty data.  Caller must ensure that the
+ * inodes have been locked against any other modifications.
+ */
+int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
+			       struct inode *inode_out, loff_t pos_out,
+			       u64 *len, bool is_dedupe)
+{
+	loff_t bs = inode_out->i_sb->s_blocksize;
+	loff_t blen;
+	loff_t isize;
+	bool same_inode = (inode_in == inode_out);
+	int ret;
+
+	/* Don't touch certain kinds of inodes */
+	if (IS_IMMUTABLE(inode_out))
+		return -EPERM;
+
+	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
+		return -ETXTBSY;
+
+	/* Don't reflink dirs, pipes, sockets... */
+	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
+		return -EISDIR;
+	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
+		return -EINVAL;
+
+	/* Are we going all the way to the end? */
+	isize = i_size_read(inode_in);
+	if (isize == 0) {
+		*len = 0;
+		return 0;
+	}
+
+	/* Zero length dedupe exits immediately; reflink goes to EOF. */
+	if (*len == 0) {
+		if (is_dedupe) {
+			*len = 0;
+			return 0;
+		}
+		*len = isize - pos_in;
+	}
+
+	/* Ensure offsets don't wrap and the input is inside i_size */
+	if (pos_in + *len < pos_in || pos_out + *len < pos_out ||
+	    pos_in + *len > isize)
+		return -EINVAL;
+
+	/* Don't allow dedupe past EOF in the dest file */
+	if (is_dedupe) {
+		loff_t	disize;
+
+		disize = i_size_read(inode_out);
+		if (pos_out >= disize || pos_out + *len > disize)
+			return -EINVAL;
+	}
+
+	/* If we're linking to EOF, continue to the block boundary. */
+	if (pos_in + *len == isize)
+		blen = ALIGN(isize, bs) - pos_in;
+	else
+		blen = *len;
+
+	/* Only reflink if we're aligned to block boundaries */
+	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
+	    !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
+		return -EINVAL;
+
+	/* Don't allow overlapped reflink within the same file */
+	if (same_inode) {
+		if (pos_out + blen > pos_in && pos_out < pos_in + blen)
+			return -EINVAL;
+	}
+
+	/* Wait for the completion of any pending IOs on both files */
+	inode_dio_wait(inode_in);
+	if (!same_inode)
+		inode_dio_wait(inode_out);
+
+	ret = filemap_write_and_wait_range(inode_in->i_mapping,
+			pos_in, pos_in + *len - 1);
+	if (ret)
+		return ret;
+
+	ret = filemap_write_and_wait_range(inode_out->i_mapping,
+			pos_out, pos_out + *len - 1);
+	if (ret)
+		return ret;
+
+	/*
+	 * Check that the extents are the same.
+	 */
+	if (is_dedupe) {
+		bool		is_same = false;
+
+		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
+				inode_out, pos_out, *len, &is_same);
+		if (ret)
+			return ret;
+		if (!is_same)
+			return -EBADE;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(vfs_clone_file_prep_inodes);
+
 int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 		struct file *file_out, loff_t pos_out, u64 len)
 {
@@ -1698,6 +1823,102 @@ int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 }
 EXPORT_SYMBOL(vfs_clone_file_range);
 
+/*
+ * Read a page's worth of file data into the page cache.  Return the page
+ * locked.
+ */
+static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
+{
+	struct address_space *mapping;
+	struct page *page;
+	pgoff_t n;
+
+	n = offset >> PAGE_SHIFT;
+	mapping = inode->i_mapping;
+	page = read_mapping_page(mapping, n, NULL);
+	if (IS_ERR(page))
+		return page;
+	if (!PageUptodate(page)) {
+		put_page(page);
+		return ERR_PTR(-EIO);
+	}
+	lock_page(page);
+	return page;
+}
+
+/*
+ * Compare extents of two files to see if they are the same.
+ * Caller must have locked both inodes to prevent write races.
+ */
+int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
+				  struct inode *dest, loff_t destoff,
+				  loff_t len, bool *is_same)
+{
+	loff_t src_poff;
+	loff_t dest_poff;
+	void *src_addr;
+	void *dest_addr;
+	struct page *src_page;
+	struct page *dest_page;
+	loff_t cmp_len;
+	bool same;
+	int error;
+
+	error = -EINVAL;
+	same = true;
+	while (len) {
+		src_poff = srcoff & (PAGE_SIZE - 1);
+		dest_poff = destoff & (PAGE_SIZE - 1);
+		cmp_len = min(PAGE_SIZE - src_poff,
+			      PAGE_SIZE - dest_poff);
+		cmp_len = min(cmp_len, len);
+		if (cmp_len <= 0)
+			goto out_error;
+
+		src_page = vfs_dedupe_get_page(src, srcoff);
+		if (IS_ERR(src_page)) {
+			error = PTR_ERR(src_page);
+			goto out_error;
+		}
+		dest_page = vfs_dedupe_get_page(dest, destoff);
+		if (IS_ERR(dest_page)) {
+			error = PTR_ERR(dest_page);
+			unlock_page(src_page);
+			put_page(src_page);
+			goto out_error;
+		}
+		src_addr = kmap_atomic(src_page);
+		dest_addr = kmap_atomic(dest_page);
+
+		flush_dcache_page(src_page);
+		flush_dcache_page(dest_page);
+
+		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
+			same = false;
+
+		kunmap_atomic(dest_addr);
+		kunmap_atomic(src_addr);
+		unlock_page(dest_page);
+		unlock_page(src_page);
+		put_page(dest_page);
+		put_page(src_page);
+
+		if (!same)
+			break;
+
+		srcoff += cmp_len;
+		destoff += cmp_len;
+		len -= cmp_len;
+	}
+
+	*is_same = same;
+	return 0;
+
+out_error:
+	return error;
+}
+EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
+
 int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
 {
 	struct file_dedupe_range_info *info;
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 0a6ad4e71e88..e314cb30a181 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -802,7 +802,7 @@ static int reiserfs_acquire_dquot(struct dquot *);
 static int reiserfs_release_dquot(struct dquot *);
 static int reiserfs_mark_dquot_dirty(struct dquot *);
 static int reiserfs_write_info(struct super_block *, int);
-static int reiserfs_quota_on(struct super_block *, int, int, struct path *);
+static int reiserfs_quota_on(struct super_block *, int, int, const struct path *);
 
 static const struct dquot_operations reiserfs_quota_operations = {
 	.write_dquot = reiserfs_write_dquot,
@@ -2348,7 +2348,7 @@ static int reiserfs_quota_on_mount(struct super_block *sb, int type)
  * Standard function to be called on quota_on
  */
 static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
-			     struct path *path)
+			     const struct path *path)
 {
 	int err;
 	struct inode *inode;
diff --git a/fs/statfs.c b/fs/statfs.c
index 083dc0ac9140..13ae259d4879 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -63,7 +63,7 @@ static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
 	return retval;
 }
 
-int vfs_statfs(struct path *path, struct kstatfs *buf)
+int vfs_statfs(const struct path *path, struct kstatfs *buf)
 {
 	int error;
 
diff --git a/fs/utimes.c b/fs/utimes.c
index 22307cdf7014..5fdb505e307c 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -48,7 +48,7 @@ static bool nsec_valid(long nsec)
 	return nsec >= 0 && nsec <= 999999999;
 }
 
-static int utimes_common(struct path *path, struct timespec *times)
+static int utimes_common(const struct path *path, struct timespec *times)
 {
 	int error;
 	struct iattr newattrs;
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 65d27a502909..bbb9eb6811b2 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -848,24 +848,6 @@ out_unlock:
 	return error;
 }
 
-STATIC ssize_t
-xfs_file_copy_range(
-	struct file	*file_in,
-	loff_t		pos_in,
-	struct file	*file_out,
-	loff_t		pos_out,
-	size_t		len,
-	unsigned int	flags)
-{
-	int		error;
-
-	error = xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-				     len, false);
-	if (error)
-		return error;
-	return len;
-}
-
 STATIC int
 xfs_file_clone_range(
 	struct file	*file_in,
@@ -1549,7 +1531,6 @@ const struct file_operations xfs_file_operations = {
 	.fsync		= xfs_file_fsync,
 	.get_unmapped_area = thp_get_unmapped_area,
 	.fallocate	= xfs_file_fallocate,
-	.copy_file_range = xfs_file_copy_range,
 	.clone_file_range = xfs_file_clone_range,
 	.dedupe_file_range = xfs_file_dedupe_range,
 };
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 88fd03c66e99..aca2d4bd4303 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1114,111 +1114,6 @@ err:
 }
 
 /*
- * Read a page's worth of file data into the page cache.  Return the page
- * locked.
- */
-static struct page *
-xfs_get_page(
-	struct inode	*inode,
-	xfs_off_t	offset)
-{
-	struct address_space	*mapping;
-	struct page		*page;
-	pgoff_t			n;
-
-	n = offset >> PAGE_SHIFT;
-	mapping = inode->i_mapping;
-	page = read_mapping_page(mapping, n, NULL);
-	if (IS_ERR(page))
-		return page;
-	if (!PageUptodate(page)) {
-		put_page(page);
-		return ERR_PTR(-EIO);
-	}
-	lock_page(page);
-	return page;
-}
-
-/*
- * Compare extents of two files to see if they are the same.
- */
-static int
-xfs_compare_extents(
-	struct inode	*src,
-	xfs_off_t	srcoff,
-	struct inode	*dest,
-	xfs_off_t	destoff,
-	xfs_off_t	len,
-	bool		*is_same)
-{
-	xfs_off_t	src_poff;
-	xfs_off_t	dest_poff;
-	void		*src_addr;
-	void		*dest_addr;
-	struct page	*src_page;
-	struct page	*dest_page;
-	xfs_off_t	cmp_len;
-	bool		same;
-	int		error;
-
-	error = -EINVAL;
-	same = true;
-	while (len) {
-		src_poff = srcoff & (PAGE_SIZE - 1);
-		dest_poff = destoff & (PAGE_SIZE - 1);
-		cmp_len = min(PAGE_SIZE - src_poff,
-			      PAGE_SIZE - dest_poff);
-		cmp_len = min(cmp_len, len);
-		ASSERT(cmp_len > 0);
-
-		trace_xfs_reflink_compare_extents(XFS_I(src), srcoff, cmp_len,
-				XFS_I(dest), destoff);
-
-		src_page = xfs_get_page(src, srcoff);
-		if (IS_ERR(src_page)) {
-			error = PTR_ERR(src_page);
-			goto out_error;
-		}
-		dest_page = xfs_get_page(dest, destoff);
-		if (IS_ERR(dest_page)) {
-			error = PTR_ERR(dest_page);
-			unlock_page(src_page);
-			put_page(src_page);
-			goto out_error;
-		}
-		src_addr = kmap_atomic(src_page);
-		dest_addr = kmap_atomic(dest_page);
-
-		flush_dcache_page(src_page);
-		flush_dcache_page(dest_page);
-
-		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
-			same = false;
-
-		kunmap_atomic(dest_addr);
-		kunmap_atomic(src_addr);
-		unlock_page(dest_page);
-		unlock_page(src_page);
-		put_page(dest_page);
-		put_page(src_page);
-
-		if (!same)
-			break;
-
-		srcoff += cmp_len;
-		destoff += cmp_len;
-		len -= cmp_len;
-	}
-
-	*is_same = same;
-	return 0;
-
-out_error:
-	trace_xfs_reflink_compare_extents_error(XFS_I(dest), error, _RET_IP_);
-	return error;
-}
-
-/*
  * Link a range of blocks from one file to another.
  */
 int
@@ -1235,14 +1130,11 @@ xfs_reflink_remap_range(
 	struct inode		*inode_out = file_inode(file_out);
 	struct xfs_inode	*dest = XFS_I(inode_out);
 	struct xfs_mount	*mp = src->i_mount;
-	loff_t			bs = inode_out->i_sb->s_blocksize;
 	bool			same_inode = (inode_in == inode_out);
 	xfs_fileoff_t		sfsbno, dfsbno;
 	xfs_filblks_t		fsblen;
 	xfs_extlen_t		cowextsize;
-	loff_t			isize;
 	ssize_t			ret;
-	loff_t			blen;
 
 	if (!xfs_sb_version_hasreflink(&mp->m_sb))
 		return -EOPNOTSUPP;
@@ -1257,26 +1149,8 @@ xfs_reflink_remap_range(
 	else
 		xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL);
 
-	/* Don't touch certain kinds of inodes */
-	ret = -EPERM;
-	if (IS_IMMUTABLE(inode_out))
-		goto out_unlock;
-
-	ret = -ETXTBSY;
-	if (IS_SWAPFILE(inode_in) || IS_SWAPFILE(inode_out))
-		goto out_unlock;
-
-
-	/* Don't reflink dirs, pipes, sockets... */
-	ret = -EISDIR;
-	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
-		goto out_unlock;
+	/* Check file eligibility and prepare for block sharing. */
 	ret = -EINVAL;
-	if (S_ISFIFO(inode_in->i_mode) || S_ISFIFO(inode_out->i_mode))
-		goto out_unlock;
-	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
-		goto out_unlock;
-
 	/* Don't reflink realtime inodes */
 	if (XFS_IS_REALTIME_INODE(src) || XFS_IS_REALTIME_INODE(dest))
 		goto out_unlock;
@@ -1285,97 +1159,18 @@ xfs_reflink_remap_range(
 	if (IS_DAX(inode_in) || IS_DAX(inode_out))
 		goto out_unlock;
 
-	/* Are we going all the way to the end? */
-	isize = i_size_read(inode_in);
-	if (isize == 0) {
-		ret = 0;
-		goto out_unlock;
-	}
-
-	/* Zero length dedupe exits immediately; reflink goes to EOF. */
-	if (len == 0) {
-		if (is_dedupe) {
-			ret = 0;
-			goto out_unlock;
-		}
-		len = isize - pos_in;
-	}
-
-	/* Ensure offsets don't wrap and the input is inside i_size */
-	if (pos_in + len < pos_in || pos_out + len < pos_out ||
-	    pos_in + len > isize)
-		goto out_unlock;
-
-	/* Don't allow dedupe past EOF in the dest file */
-	if (is_dedupe) {
-		loff_t	disize;
-
-		disize = i_size_read(inode_out);
-		if (pos_out >= disize || pos_out + len > disize)
-			goto out_unlock;
-	}
-
-	/* If we're linking to EOF, continue to the block boundary. */
-	if (pos_in + len == isize)
-		blen = ALIGN(isize, bs) - pos_in;
-	else
-		blen = len;
-
-	/* Only reflink if we're aligned to block boundaries */
-	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
-	    !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
-		goto out_unlock;
-
-	/* Don't allow overlapped reflink within the same file */
-	if (same_inode) {
-		if (pos_out + blen > pos_in && pos_out < pos_in + blen)
-			goto out_unlock;
-	}
-
-	/* Wait for the completion of any pending IOs on both files */
-	inode_dio_wait(inode_in);
-	if (!same_inode)
-		inode_dio_wait(inode_out);
-
-	ret = filemap_write_and_wait_range(inode_in->i_mapping,
-			pos_in, pos_in + len - 1);
-	if (ret)
-		goto out_unlock;
-
-	ret = filemap_write_and_wait_range(inode_out->i_mapping,
-			pos_out, pos_out + len - 1);
-	if (ret)
+	ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
+			&len, is_dedupe);
+	if (ret || len == 0)
 		goto out_unlock;
 
 	trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
 
-	/*
-	 * Check that the extents are the same.
-	 */
-	if (is_dedupe) {
-		bool		is_same = false;
-
-		ret = xfs_compare_extents(inode_in, pos_in, inode_out, pos_out,
-				len, &is_same);
-		if (ret)
-			goto out_unlock;
-		if (!is_same) {
-			ret = -EBADE;
-			goto out_unlock;
-		}
-	}
-
+	/* Set flags and remap blocks. */
 	ret = xfs_reflink_set_inode_flag(src, dest);
 	if (ret)
 		goto out_unlock;
 
-	/*
-	 * Invalidate the page cache so that we can clear any CoW mappings
-	 * in the destination file.
-	 */
-	truncate_inode_pages_range(&inode_out->i_data, pos_out,
-				   PAGE_ALIGN(pos_out + len) - 1);
-
 	dfsbno = XFS_B_TO_FSBT(mp, pos_out);
 	sfsbno = XFS_B_TO_FSBT(mp, pos_in);
 	fsblen = XFS_B_TO_FSB(mp, len);
@@ -1384,6 +1179,10 @@ xfs_reflink_remap_range(
 	if (ret)
 		goto out_unlock;
 
+	/* Zap any page cache for the destination file's range. */
+	truncate_inode_pages_range(&inode_out->i_data, pos_out,
+				   PAGE_ALIGN(pos_out + len) - 1);
+
 	/*
 	 * Carry the cowextsize hint from src to dest if we're sharing the
 	 * entire source file to the entire destination file, the source file