From 49dae1bc1c665817e434d01eefaa11967f618243 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Sat, 6 Sep 2014 22:34:39 +0100 Subject: Btrfs: fix fsync data loss after a ranged fsync While we're doing a full fsync (when the inode has the flag BTRFS_INODE_NEEDS_FULL_SYNC set) that is ranged too (covers only a portion of the file), we might have ordered operations that are started before or while we're logging the inode and that fall outside the fsync range. Therefore when a full ranged fsync finishes don't remove every extent map from the list of modified extent maps - as for some of them, that fall outside our fsync range, their respective ordered operation hasn't finished yet, meaning the corresponding file extent item wasn't inserted into the fs/subvol tree yet and therefore we didn't log it, and we must let the next fast fsync (one that checks only the modified list) see this extent map and log a matching file extent item to the log btree and wait for its ordered operation to finish (if it's still ongoing). A test case for xfstests follows. Signed-off-by: Filipe Manana Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 77 ++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 61 insertions(+), 16 deletions(-) (limited to 'fs/btrfs/tree-log.c') diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 7e0e6e3029dd..d296efe2d3e7 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -94,8 +94,10 @@ #define LOG_WALK_REPLAY_ALL 3 static int btrfs_log_inode(struct btrfs_trans_handle *trans, - struct btrfs_root *root, struct inode *inode, - int inode_only); + struct btrfs_root *root, struct inode *inode, + int inode_only, + const loff_t start, + const loff_t end); static int link_to_fixup_dir(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u64 objectid); @@ -3858,8 +3860,10 @@ process: * This handles both files and directories. */ static int btrfs_log_inode(struct btrfs_trans_handle *trans, - struct btrfs_root *root, struct inode *inode, - int inode_only) + struct btrfs_root *root, struct inode *inode, + int inode_only, + const loff_t start, + const loff_t end) { struct btrfs_path *path; struct btrfs_path *dst_path; @@ -3876,6 +3880,7 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans, int ins_nr; bool fast_search = false; u64 ino = btrfs_ino(inode); + struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; path = btrfs_alloc_path(); if (!path) @@ -4049,13 +4054,35 @@ log_extents: goto out_unlock; } } else if (inode_only == LOG_INODE_ALL) { - struct extent_map_tree *tree = &BTRFS_I(inode)->extent_tree; struct extent_map *em, *n; - write_lock(&tree->lock); - list_for_each_entry_safe(em, n, &tree->modified_extents, list) - list_del_init(&em->list); - write_unlock(&tree->lock); + write_lock(&em_tree->lock); + /* + * We can't just remove every em if we're called for a ranged + * fsync - that is, one that doesn't cover the whole possible + * file range (0 to LLONG_MAX). This is because we can have + * em's that fall outside the range we're logging and therefore + * their ordered operations haven't completed yet + * (btrfs_finish_ordered_io() not invoked yet). This means we + * didn't get their respective file extent item in the fs/subvol + * tree yet, and need to let the next fast fsync (one which + * consults the list of modified extent maps) find the em so + * that it logs a matching file extent item and waits for the + * respective ordered operation to complete (if it's still + * running). + * + * Removing every em outside the range we're logging would make + * the next fast fsync not log their matching file extent items, + * therefore making us lose data after a log replay. + */ + list_for_each_entry_safe(em, n, &em_tree->modified_extents, + list) { + const u64 mod_end = em->mod_start + em->mod_len - 1; + + if (em->mod_start >= start && mod_end <= end) + list_del_init(&em->list); + } + write_unlock(&em_tree->lock); } if (inode_only == LOG_INODE_ALL && S_ISDIR(inode->i_mode)) { @@ -4065,8 +4092,19 @@ log_extents: goto out_unlock; } } - BTRFS_I(inode)->logged_trans = trans->transid; - BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->last_sub_trans; + + write_lock(&em_tree->lock); + /* + * If we're doing a ranged fsync and there are still modified extents + * in the list, we must run on the next fsync call as it might cover + * those extents (a full fsync or an fsync for other range). + */ + if (list_empty(&em_tree->modified_extents)) { + BTRFS_I(inode)->logged_trans = trans->transid; + BTRFS_I(inode)->last_log_commit = + BTRFS_I(inode)->last_sub_trans; + } + write_unlock(&em_tree->lock); out_unlock: if (unlikely(err)) btrfs_put_logged_extents(&logged_list); @@ -4161,7 +4199,10 @@ out: */ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, - struct dentry *parent, int exists_only, + struct dentry *parent, + const loff_t start, + const loff_t end, + int exists_only, struct btrfs_log_ctx *ctx) { int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL; @@ -4207,7 +4248,7 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (ret) goto end_no_trans; - ret = btrfs_log_inode(trans, root, inode, inode_only); + ret = btrfs_log_inode(trans, root, inode, inode_only, start, end); if (ret) goto end_trans; @@ -4235,7 +4276,8 @@ static int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (BTRFS_I(inode)->generation > root->fs_info->last_trans_committed) { - ret = btrfs_log_inode(trans, root, inode, inode_only); + ret = btrfs_log_inode(trans, root, inode, inode_only, + 0, LLONG_MAX); if (ret) goto end_trans; } @@ -4269,13 +4311,15 @@ end_no_trans: */ int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct dentry *dentry, + const loff_t start, + const loff_t end, struct btrfs_log_ctx *ctx) { struct dentry *parent = dget_parent(dentry); int ret; ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, - 0, ctx); + start, end, 0, ctx); dput(parent); return ret; @@ -4512,6 +4556,7 @@ int btrfs_log_new_name(struct btrfs_trans_handle *trans, root->fs_info->last_trans_committed)) return 0; - return btrfs_log_inode_parent(trans, root, inode, parent, 1, NULL); + return btrfs_log_inode_parent(trans, root, inode, parent, 0, + LLONG_MAX, 1, NULL); } -- cgit v1.2.1