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authorLiu Bo <bo.li.liu@oracle.com>2017-09-01 16:14:30 -0600
committerDavid Sterba <dsterba@suse.com>2017-10-30 12:27:55 +0100
commit49e83f5735cf1aca03ca8b4eadca475c1f3b0b14 (patch)
tree39541ef4b34a4fcbd9efb91ed90dac62f5567e4c /fs/btrfs/tree-log.c
parent45bac0f3d24a76f127a118e7b95a54e616449d16 (diff)
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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.c30
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,