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authorZhao Lei <zhaolei@cn.fujitsu.com>2016-01-26 13:42:40 +0300
committerDavid Sterba <dsterba@suse.com>2016-02-18 12:27:23 +0300
commit4fe7a0e13864238fe5b4cc2640e963581f96429e (patch)
tree6bbeac8bc14b6fa2683c454cafea277f1be88022 /fs/btrfs/reada.c
parent2fefd5583f8b86171c898f90cadac7c09ccf9d73 (diff)
downloadlinux-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.c9
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);