diff options
Diffstat (limited to 'fs/ocfs2/dlmglue.c')
| -rw-r--r-- | fs/ocfs2/dlmglue.c | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c index fa5e3bdc295d..3867244fb144 100644 --- a/fs/ocfs2/dlmglue.c +++ b/fs/ocfs2/dlmglue.c @@ -68,6 +68,7 @@ struct ocfs2_mask_waiter { static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres); static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres); +static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres); /* * Return value from ->downconvert_worker functions. @@ -252,6 +253,11 @@ static struct ocfs2_lock_res_ops ocfs2_inode_open_lops = { .flags = 0, }; +static struct ocfs2_lock_res_ops ocfs2_flock_lops = { + .get_osb = ocfs2_get_file_osb, + .flags = 0, +}; + static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres) { return lockres->l_type == OCFS2_LOCK_TYPE_META || @@ -310,6 +316,17 @@ static int ocfs2_inode_lock_update(struct inode *inode, struct buffer_head **bh); static void ocfs2_drop_osb_locks(struct ocfs2_super *osb); static inline int ocfs2_highest_compat_lock_level(int level); +static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres, + int new_level); +static int ocfs2_downconvert_lock(struct ocfs2_super *osb, + struct ocfs2_lock_res *lockres, + int new_level, + int lvb); +static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb, + struct ocfs2_lock_res *lockres); +static int ocfs2_cancel_convert(struct ocfs2_super *osb, + struct ocfs2_lock_res *lockres); + static void ocfs2_build_lock_name(enum ocfs2_lock_type type, u64 blkno, @@ -419,6 +436,13 @@ static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres) return OCFS2_SB(inode->i_sb); } +static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres) +{ + struct ocfs2_file_private *fp = lockres->l_priv; + + return OCFS2_SB(fp->fp_file->f_mapping->host->i_sb); +} + static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres) { __be64 inode_blkno_be; @@ -499,6 +523,21 @@ static void ocfs2_rename_lock_res_init(struct ocfs2_lock_res *res, &ocfs2_rename_lops, osb); } +void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres, + struct ocfs2_file_private *fp) +{ + struct inode *inode = fp->fp_file->f_mapping->host; + struct ocfs2_inode_info *oi = OCFS2_I(inode); + + ocfs2_lock_res_init_once(lockres); + ocfs2_build_lock_name(OCFS2_LOCK_TYPE_FLOCK, oi->ip_blkno, + inode->i_generation, lockres->l_name); + ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres, + OCFS2_LOCK_TYPE_FLOCK, &ocfs2_flock_lops, + fp); + lockres->l_flags |= OCFS2_LOCK_NOCACHE; +} + void ocfs2_lock_res_free(struct ocfs2_lock_res *res) { mlog_entry_void(); @@ -715,6 +754,13 @@ static void ocfs2_blocking_ast(void *opaque, int level) lockres->l_name, level, lockres->l_level, ocfs2_lock_type_string(lockres->l_type)); + /* + * We can skip the bast for locks which don't enable caching - + * they'll be dropped at the earliest possible time anyway. + */ + if (lockres->l_flags & OCFS2_LOCK_NOCACHE) + return; + spin_lock_irqsave(&lockres->l_lock, flags); needs_downconvert = ocfs2_generic_handle_bast(lockres, level); if (needs_downconvert) @@ -926,6 +972,21 @@ static int lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres, } +static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw, + struct ocfs2_lock_res *lockres) +{ + int ret; + + ret = wait_for_completion_interruptible(&mw->mw_complete); + if (ret) + lockres_remove_mask_waiter(lockres, mw); + else + ret = mw->mw_status; + /* Re-arm the completion in case we want to wait on it again */ + INIT_COMPLETION(mw->mw_complete); + return ret; +} + static int ocfs2_cluster_lock(struct ocfs2_super *osb, struct ocfs2_lock_res *lockres, int level, @@ -1296,6 +1357,212 @@ out: mlog_exit_void(); } +static int ocfs2_flock_handle_signal(struct ocfs2_lock_res *lockres, + int level) +{ + int ret; + struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres); + unsigned long flags; + struct ocfs2_mask_waiter mw; + + ocfs2_init_mask_waiter(&mw); + +retry_cancel: + spin_lock_irqsave(&lockres->l_lock, flags); + if (lockres->l_flags & OCFS2_LOCK_BUSY) { + ret = ocfs2_prepare_cancel_convert(osb, lockres); + if (ret) { + spin_unlock_irqrestore(&lockres->l_lock, flags); + ret = ocfs2_cancel_convert(osb, lockres); + if (ret < 0) { + mlog_errno(ret); + goto out; + } + goto retry_cancel; + } + lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0); + spin_unlock_irqrestore(&lockres->l_lock, flags); + + ocfs2_wait_for_mask(&mw); + goto retry_cancel; + } + + ret = -ERESTARTSYS; + /* + * We may still have gotten the lock, in which case there's no + * point to restarting the syscall. + */ + if (lockres->l_level == level) + ret = 0; + + mlog(0, "Cancel returning %d. flags: 0x%lx, level: %d, act: %d\n", ret, + lockres->l_flags, lockres->l_level, lockres->l_action); + + spin_unlock_irqrestore(&lockres->l_lock, flags); + +out: + return ret; +} + +/* + * ocfs2_file_lock() and ocfs2_file_unlock() map to a single pair of + * flock() calls. The locking approach this requires is sufficiently + * different from all other cluster lock types that we implement a + * seperate path to the "low-level" dlm calls. In particular: + * + * - No optimization of lock levels is done - we take at exactly + * what's been requested. + * + * - No lock caching is employed. We immediately downconvert to + * no-lock at unlock time. This also means flock locks never go on + * the blocking list). + * + * - Since userspace can trivially deadlock itself with flock, we make + * sure to allow cancellation of a misbehaving applications flock() + * request. + * + * - Access to any flock lockres doesn't require concurrency, so we + * can simplify the code by requiring the caller to guarantee + * serialization of dlmglue flock calls. + */ +int ocfs2_file_lock(struct file *file, int ex, int trylock) +{ + int ret, level = ex ? LKM_EXMODE : LKM_PRMODE; + unsigned int lkm_flags = trylock ? LKM_NOQUEUE : 0; + unsigned long flags; + struct ocfs2_file_private *fp = file->private_data; + struct ocfs2_lock_res *lockres = &fp->fp_flock; + struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb); + struct ocfs2_mask_waiter mw; + + ocfs2_init_mask_waiter(&mw); + + if ((lockres->l_flags & OCFS2_LOCK_BUSY) || + (lockres->l_level > LKM_NLMODE)) { + mlog(ML_ERROR, + "File lock \"%s\" has busy or locked state: flags: 0x%lx, " + "level: %u\n", lockres->l_name, lockres->l_flags, + lockres->l_level); + return -EINVAL; + } + + spin_lock_irqsave(&lockres->l_lock, flags); + if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) { + lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0); + spin_unlock_irqrestore(&lockres->l_lock, flags); + + /* + * Get the lock at NLMODE to start - that way we + * can cancel the upconvert request if need be. + */ + ret = ocfs2_lock_create(osb, lockres, LKM_NLMODE, 0); + if (ret < 0) { + mlog_errno(ret); + goto out; + } + + ret = ocfs2_wait_for_mask(&mw); + if (ret) { + mlog_errno(ret); + goto out; + } + spin_lock_irqsave(&lockres->l_lock, flags); + } + + lockres->l_action = OCFS2_AST_CONVERT; + lkm_flags |= LKM_CONVERT; + lockres->l_requested = level; + lockres_or_flags(lockres, OCFS2_LOCK_BUSY); + + lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0); + spin_unlock_irqrestore(&lockres->l_lock, flags); + + ret = dlmlock(osb->dlm, level, &lockres->l_lksb, lkm_flags, + lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1, + ocfs2_locking_ast, lockres, ocfs2_blocking_ast); + if (ret != DLM_NORMAL) { + if (trylock && ret == DLM_NOTQUEUED) + ret = -EAGAIN; + else { + ocfs2_log_dlm_error("dlmlock", ret, lockres); + ret = -EINVAL; + } + + ocfs2_recover_from_dlm_error(lockres, 1); + lockres_remove_mask_waiter(lockres, &mw); + goto out; + } + + ret = ocfs2_wait_for_mask_interruptible(&mw, lockres); + if (ret == -ERESTARTSYS) { + /* + * Userspace can cause deadlock itself with + * flock(). Current behavior locally is to allow the + * deadlock, but abort the system call if a signal is + * received. We follow this example, otherwise a + * poorly written program could sit in kernel until + * reboot. + * + * Handling this is a bit more complicated for Ocfs2 + * though. We can't exit this function with an + * outstanding lock request, so a cancel convert is + * required. We intentionally overwrite 'ret' - if the + * cancel fails and the lock was granted, it's easier + * to just bubble sucess back up to the user. + */ + ret = ocfs2_flock_handle_signal(lockres, level); + } + +out: + + mlog(0, "Lock: \"%s\" ex: %d, trylock: %d, returns: %d\n", + lockres->l_name, ex, trylock, ret); + return ret; +} + +void ocfs2_file_unlock(struct file *file) +{ + int ret; + unsigned long flags; + struct ocfs2_file_private *fp = file->private_data; + struct ocfs2_lock_res *lockres = &fp->fp_flock; + struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb); + struct ocfs2_mask_waiter mw; + + ocfs2_init_mask_waiter(&mw); + + if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) + return; + + if (lockres->l_level == LKM_NLMODE) + return; + + mlog(0, "Unlock: \"%s\" flags: 0x%lx, level: %d, act: %d\n", + lockres->l_name, lockres->l_flags, lockres->l_level, + lockres->l_action); + + spin_lock_irqsave(&lockres->l_lock, flags); + /* + * Fake a blocking ast for the downconvert code. + */ + lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED); + lockres->l_blocking = LKM_EXMODE; + + ocfs2_prepare_downconvert(lockres, LKM_NLMODE); + lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0); + spin_unlock_irqrestore(&lockres->l_lock, flags); + + ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0); + if (ret) { + mlog_errno(ret); + return; + } + + ret = ocfs2_wait_for_mask(&mw); + if (ret) + mlog_errno(ret); +} + static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb, struct ocfs2_lock_res *lockres) { |
