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| author | Zhao Lei <zhaolei@cn.fujitsu.com> | 2016-01-26 13:42:40 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2016-02-18 12:27:23 +0300 |
| commit | 4fe7a0e13864238fe5b4cc2640e963581f96429e (patch) | |
| tree | 6bbeac8bc14b6fa2683c454cafea277f1be88022 /fs/btrfs/reada.c | |
| parent | 2fefd5583f8b86171c898f90cadac7c09ccf9d73 (diff) | |
| download | linux-4fe7a0e13864238fe5b4cc2640e963581f96429e.tar.xz | |
btrfs: reada: avoid undone reada extents in btrfs_reada_wait
Reada background works is not designed to finish all jobs
completely, it will break in following case:
1: When a device reaches workload limit (MAX_IN_FLIGHT)
2: Total reads reach max limit (10000)
3: All devices don't have queued more jobs, often happened in DUP case
And if all background works exit with remaining jobs,
btrfs_reada_wait() will wait indefinetelly.
Above problem is rarely happened in old code, because:
1: Every work queues 2x new works
So many works reduced chances of undone jobs.
2: One work will continue 10000 times loop in case of no-jobs
It reduced no-thread window time.
But after we fixed above case, the "undone reada extents" frequently
happened.
Fix:
Check to ensure we have at least one thread if there are undone jobs
in btrfs_reada_wait().
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/reada.c')
| -rw-r--r-- | fs/btrfs/reada.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c index e97bc8eb01e2..5bcd567f4827 100644 --- a/fs/btrfs/reada.c +++ b/fs/btrfs/reada.c @@ -953,8 +953,11 @@ struct reada_control *btrfs_reada_add(struct btrfs_root *root, int btrfs_reada_wait(void *handle) { struct reada_control *rc = handle; + struct btrfs_fs_info *fs_info = rc->root->fs_info; while (atomic_read(&rc->elems)) { + if (!atomic_read(&fs_info->reada_works_cnt)) + reada_start_machine(fs_info); wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, 5 * HZ); dump_devs(rc->root->fs_info, @@ -971,9 +974,13 @@ int btrfs_reada_wait(void *handle) int btrfs_reada_wait(void *handle) { struct reada_control *rc = handle; + struct btrfs_fs_info *fs_info = rc->root->fs_info; while (atomic_read(&rc->elems)) { - wait_event(rc->wait, atomic_read(&rc->elems) == 0); + if (!atomic_read(&fs_info->reada_works_cnt)) + reada_start_machine(fs_info); + wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0, + (HZ + 9) / 10); } kref_put(&rc->refcnt, reada_control_release); |