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| author |   Mikulas Patocka <mpatocka@redhat.com> | 2022-08-10 16:16:34 -0400 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@kernel.org> | 2022-08-11 11:10:42 -0400 |
| commit | e3a7c2947b9e01b9cedd3f67849c0ae95f0fadfa (patch) | |
| tree | c7710728a55e2a9b042beda3c95b6ab28cd609b8 /drivers/md | |
| parent | dm writecache: fix smatch warning about invalid return from writecache_map (diff) | |
| download | linux-dev-e3a7c2947b9e01b9cedd3f67849c0ae95f0fadfa.tar.xz linux-dev-e3a7c2947b9e01b9cedd3f67849c0ae95f0fadfa.zip | |
dm bufio: fix some cases where the code sleeps with spinlock held
Commit b32d45824aa7 ("dm bufio: Add DM_BUFIO_CLIENT_NO_SLEEP flag")
added a "NO_SLEEP" mode, it replaces a mutex with a spinlock, and it
is only usable when the device is in read-only mode (because the write
path may be sleeping while holding the dm_bufio_client lock).
However, there are still two points where the code could sleep even in
read-only mode. One is in __get_unclaimed_buffer -> __make_buffer_clean.
The other is in __try_evict_buffer -> __make_buffer_clean. These functions
will call __make_buffer_clean which sleeps if the buffer is being read.
Fix these cases so that if c->no_sleep is set __make_buffer_clean
will not be called and the buffer will be skipped instead.
Fixes: b32d45824aa7 ("dm bufio: Add DM_BUFIO_CLIENT_NO_SLEEP flag")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-bufio.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index bef8c6eb5bdb..799915220e6c 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -815,6 +815,10 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) BUG_ON(test_bit(B_WRITING, &b->state)); BUG_ON(test_bit(B_DIRTY, &b->state)); + if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep && + unlikely(test_bit(B_READING, &b->state))) + continue; + if (!b->hold_count) { __make_buffer_clean(b); __unlink_buffer(b); @@ -823,6 +827,9 @@ static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c) cond_resched(); } + if (static_branch_unlikely(&no_sleep_enabled) && c->no_sleep) + return NULL; + list_for_each_entry_reverse(b, &c->lru[LIST_DIRTY], lru_list) { BUG_ON(test_bit(B_READING, &b->state)); @@ -1632,7 +1639,8 @@ static void drop_buffers(struct dm_bufio_client *c) */ static bool __try_evict_buffer(struct dm_buffer *b, gfp_t gfp) { - if (!(gfp & __GFP_FS)) { + if (!(gfp & __GFP_FS) || + (static_branch_unlikely(&no_sleep_enabled) && b->c->no_sleep)) { if (test_bit(B_READING, &b->state) || test_bit(B_WRITING, &b->state) || test_bit(B_DIRTY, &b->state)) |