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| author | Liu Bo <bo.li.liu@oracle.com> | 2017-09-02 01:14:30 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2017-10-30 14:27:55 +0300 |
| commit | 49e83f5735cf1aca03ca8b4eadca475c1f3b0b14 (patch) | |
| tree | 39541ef4b34a4fcbd9efb91ed90dac62f5567e4c /fs/btrfs/tree-log.c | |
| parent | 45bac0f3d24a76f127a118e7b95a54e616449d16 (diff) | |
| download | linux-49e83f5735cf1aca03ca8b4eadca475c1f3b0b14.tar.xz | |
Btrfs: protect conditions within root->log_mutex while waiting
Both wait_for_commit() and wait_for_writer() are checking the
condition out of the mutex lock.
This refactors code a bit to be lock safe.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tree-log.c')
| -rw-r--r-- | fs/btrfs/tree-log.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index c800d067fcbf..963f22b17508 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -2699,34 +2699,36 @@ static void wait_log_commit(struct btrfs_root *root, int transid) * so we know that if ours is more than 2 older than the * current transaction, we're done */ - do { + for (;;) { prepare_to_wait(&root->log_commit_wait[index], &wait, TASK_UNINTERRUPTIBLE); - mutex_unlock(&root->log_mutex); - if (root->log_transid_committed < transid && - atomic_read(&root->log_commit[index])) - schedule(); + if (!(root->log_transid_committed < transid && + atomic_read(&root->log_commit[index]))) + break; - finish_wait(&root->log_commit_wait[index], &wait); + mutex_unlock(&root->log_mutex); + schedule(); mutex_lock(&root->log_mutex); - } while (root->log_transid_committed < transid && - atomic_read(&root->log_commit[index])); + } + finish_wait(&root->log_commit_wait[index], &wait); } static void wait_for_writer(struct btrfs_root *root) { DEFINE_WAIT(wait); - while (atomic_read(&root->log_writers)) { - prepare_to_wait(&root->log_writer_wait, - &wait, TASK_UNINTERRUPTIBLE); + for (;;) { + prepare_to_wait(&root->log_writer_wait, &wait, + TASK_UNINTERRUPTIBLE); + if (!atomic_read(&root->log_writers)) + break; + mutex_unlock(&root->log_mutex); - if (atomic_read(&root->log_writers)) - schedule(); - finish_wait(&root->log_writer_wait, &wait); + schedule(); mutex_lock(&root->log_mutex); } + finish_wait(&root->log_writer_wait, &wait); } static inline void btrfs_remove_log_ctx(struct btrfs_root *root, |