On Thu, Oct 13 2011 at 11:05am -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > Hi > > I found a way how to shut up lockdep warnings in dm-bufio, so you can > download new a version which uses nested locks from > http://people.redhat.com/mpatocka/patches/kernel/dm-thinp-bufio/ > > BTW. why did you move dm-bufio to persistent-data directory? What are > other dm-bufio users (such as dm-zeroed or dm-multisnap) going to do? I > thought dm-bufio should be a separate module available to all device > mapper targets, such as dm-io, dm-kcopyd or so? Here is a patch with your nested lock fix that applies to Joe's thin-dev branch (note that the dm-bufio in thin-dev branch has been cleaned up some so this took a bit of care; Mikulas would be nice if you reviewed those changes): drivers/md/persistent-data/dm-bufio.c | 71 ++++++++++++++++++++++----------- 1 files changed, 48 insertions(+), 23 deletions(-) diff --git a/drivers/md/persistent-data/dm-bufio.c b/drivers/md/persistent-data/dm-bufio.c index 6be4386..e7d1aac 100644 --- a/drivers/md/persistent-data/dm-bufio.c +++ b/drivers/md/persistent-data/dm-bufio.c @@ -151,6 +151,23 @@ static inline int dm_bufio_cache_index(struct dm_bufio_client *c) #define DM_BUFIO_CACHE(c) (dm_bufio_caches[dm_bufio_cache_index(c)]) #define DM_BUFIO_CACHE_NAME(c) (dm_bufio_cache_names[dm_bufio_cache_index(c)]) +#define dm_bufio_in_request() (!!current->bio_list) + +static void dm_bufio_lock(struct dm_bufio_client *c) +{ + mutex_lock_nested(&c->lock, dm_bufio_in_request()); +} + +static int dm_bufio_trylock(struct dm_bufio_client *c) +{ + return dm_bufio_trylock(c); +} + +static void dm_bufio_unlock(struct dm_bufio_client *c) +{ + dm_bufio_unlock(c); +} + /*----------------------------------------------------------------*/ /* Default cache size --- available memory divided by the ratio */ @@ -595,14 +612,14 @@ static void __wait_for_free_buffer(struct dm_bufio_client *c) add_wait_queue(&c->free_buffer_wait, &wait); set_task_state(current, TASK_UNINTERRUPTIBLE); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); io_schedule(); set_task_state(current, TASK_RUNNING); remove_wait_queue(&c->free_buffer_wait, &wait); - mutex_lock(&c->lock); + dm_bufio_lock(c); } /* @@ -836,9 +853,9 @@ static void *new_read(struct dm_bufio_client *c, sector_t block, enum new_flag n int need_submit; struct dm_buffer *b; - mutex_lock(&c->lock); + dm_bufio_lock(c); b = __bufio_new(c, block, nf, bp, &need_submit); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); if (!b || IS_ERR(b)) return b; @@ -867,19 +884,21 @@ void *dm_bufio_get(struct dm_bufio_client *c, sector_t block, void *dm_bufio_read(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { + BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_READ, bp); } void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp) { + BUG_ON(dm_bufio_in_request()); return new_read(c, block, NF_FRESH, bp); } void dm_bufio_release(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; - mutex_lock(&c->lock); + dm_bufio_lock(c); BUG_ON(test_bit(B_READING, &b->state)); BUG_ON(!b->hold_count); b->hold_count--; @@ -898,26 +917,27 @@ void dm_bufio_release(struct dm_buffer *b) __free_buffer_wake(b); } } - mutex_unlock(&c->lock); + dm_bufio_unlock(c); } void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; - mutex_lock(&c->lock); + dm_bufio_lock(c); if (!test_and_set_bit(B_DIRTY, &b->state)) __relink_lru(b, LIST_DIRTY); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); } void dm_bufio_write_dirty_buffers_async(struct dm_bufio_client *c) { - mutex_lock(&c->lock); + BUG_ON(dm_bufio_in_request()); + dm_bufio_lock(c); __write_dirty_buffers_async(c, 0); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); } /* @@ -933,7 +953,7 @@ int dm_bufio_write_dirty_buffers(struct dm_bufio_client *c) unsigned long buffers_processed = 0; struct dm_buffer *b, *tmp; - mutex_lock(&c->lock); + dm_bufio_lock(c); __write_dirty_buffers_async(c, 0); again: @@ -947,10 +967,10 @@ again: if (buffers_processed < c->n_buffers[LIST_DIRTY]) { dropped_lock = 1; b->hold_count++; - mutex_unlock(&c->lock); + dm_bufio_unlock(c); wait_on_bit(&b->state, B_WRITING, do_io_schedule, TASK_UNINTERRUPTIBLE); - mutex_lock(&c->lock); + dm_bufio_lock(c); b->hold_count--; } else wait_on_bit(&b->state, B_WRITING, @@ -978,7 +998,7 @@ again: goto again; } wake_up(&c->free_buffer_wait); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); a = xchg(&c->async_write_error, 0); f = dm_bufio_issue_flush(c); @@ -1003,6 +1023,7 @@ int dm_bufio_issue_flush(struct dm_bufio_client *c) .sector = 0, .count = 0, }; + BUG_ON(dm_bufio_in_request()); return dm_io(&io_req, 1, &io_reg, NULL); } @@ -1023,7 +1044,9 @@ void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block) struct dm_bufio_client *c = b->c; struct dm_buffer *new; - mutex_lock(&c->lock); + BUG_ON(dm_bufio_in_request()); + + dm_bufio_lock(c); retry: new = __find(c, new_block); @@ -1054,7 +1077,7 @@ retry: wait_on_bit(&b->state, B_WRITING, do_io_schedule, TASK_UNINTERRUPTIBLE); } - mutex_unlock(&c->lock); + dm_bufio_unlock(c); dm_bufio_release(b); } @@ -1094,10 +1117,12 @@ static void drop_buffers(struct dm_bufio_client *c) struct dm_buffer *b; int i; + BUG_ON(dm_bufio_in_request()); + /* an optimization ... so that the buffers are not written one-by-one */ dm_bufio_write_dirty_buffers_async(c); - mutex_lock(&c->lock); + dm_bufio_lock(c); while ((b = __get_unclaimed_buffer(c))) __free_buffer_wake(b); @@ -1110,7 +1135,7 @@ static void drop_buffers(struct dm_bufio_client *c) for (i = 0; i < LIST_N; i++) BUG_ON(!list_empty(&c->lru[i])); - mutex_unlock(&c->lock); + dm_bufio_unlock(c); } /* @@ -1166,9 +1191,9 @@ static int shrink(struct shrinker *shrinker, struct shrink_control *sc) unsigned long nr_to_scan = sc->nr_to_scan; if (sc->gfp_mask & __GFP_IO) { - mutex_lock(&c->lock); + dm_bufio_lock(c); } else { - if (!mutex_trylock(&c->lock)) + if (!dm_bufio_trylock(c)) return !nr_to_scan ? 0 : -1; } @@ -1179,7 +1204,7 @@ static int shrink(struct shrinker *shrinker, struct shrink_control *sc) if (r > INT_MAX) r = INT_MAX; - mutex_unlock(&c->lock); + dm_bufio_unlock(c); return r; } @@ -1356,7 +1381,7 @@ static void cleanup_old_buffers(void) mutex_lock(&dm_bufio_clients_lock); list_for_each_entry(c, &dm_bufio_all_clients, client_list) { - if (!mutex_trylock(&c->lock)) + if (!dm_bufio_trylock(c)) continue; while (!list_empty(&c->lru[LIST_CLEAN])) { @@ -1367,7 +1392,7 @@ static void cleanup_old_buffers(void) break; } - mutex_unlock(&c->lock); + dm_bufio_unlock(c); } mutex_unlock(&dm_bufio_clients_lock); } -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
