diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/md/dm-bufio.c | 108 | ||||
| -rw-r--r-- | drivers/md/dm-bufio.h | 8 |
2 files changed, 90 insertions, 26 deletions
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index b6e58c7b6df..cc06a1e5242 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -578,7 +578,7 @@ static void write_endio(struct bio *bio, int error) struct dm_buffer *b = container_of(bio, struct dm_buffer, bio); b->write_error = error; - if (error) { + if (unlikely(error)) { struct dm_bufio_client *c = b->c; (void)cmpxchg(&c->async_write_error, 0, error); } @@ -697,13 +697,20 @@ static void __wait_for_free_buffer(struct dm_bufio_client *c) dm_bufio_lock(c); } +enum new_flag { + NF_FRESH = 0, + NF_READ = 1, + NF_GET = 2, + NF_PREFETCH = 3 +}; + /* * Allocate a new buffer. If the allocation is not possible, wait until * some other thread frees a buffer. * * May drop the lock and regain it. */ -static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c) +static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf) { struct dm_buffer *b; @@ -726,6 +733,9 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client return b; } + if (nf == NF_PREFETCH) + return NULL; + if (!list_empty(&c->reserved_buffers)) { b = list_entry(c->reserved_buffers.next, struct dm_buffer, lru_list); @@ -743,9 +753,12 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client } } -static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c) +static struct dm_buffer *__alloc_buffer_wait(struct dm_bufio_client *c, enum new_flag nf) { - struct dm_buffer *b = __alloc_buffer_wait_no_callback(c); + struct dm_buffer *b = __alloc_buffer_wait_no_callback(c, nf); + + if (!b) + return NULL; if (c->alloc_callback) c->alloc_callback(b); @@ -865,32 +878,23 @@ static struct dm_buffer *__find(struct dm_bufio_client *c, sector_t block) * Getting a buffer *--------------------------------------------------------------*/ -enum new_flag { - NF_FRESH = 0, - NF_READ = 1, - NF_GET = 2 -}; - static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, - enum new_flag nf, struct dm_buffer **bp, - int *need_submit) + enum new_flag nf, int *need_submit) { struct dm_buffer *b, *new_b = NULL; *need_submit = 0; b = __find(c, block); - if (b) { - b->hold_count++; - __relink_lru(b, test_bit(B_DIRTY, &b->state) || - test_bit(B_WRITING, &b->state)); - return b; - } + if (b) + goto found_buffer; if (nf == NF_GET) return NULL; - new_b = __alloc_buffer_wait(c); + new_b = __alloc_buffer_wait(c, nf); + if (!new_b) + return NULL; /* * We've had a period where the mutex was unlocked, so need to @@ -899,10 +903,7 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, b = __find(c, block); if (b) { __free_buffer_wake(new_b); - b->hold_count++; - __relink_lru(b, test_bit(B_DIRTY, &b->state) || - test_bit(B_WRITING, &b->state)); - return b; + goto found_buffer; } __check_watermark(c); @@ -922,6 +923,24 @@ static struct dm_buffer *__bufio_new(struct dm_bufio_client *c, sector_t block, *need_submit = 1; return b; + +found_buffer: + if (nf == NF_PREFETCH) + return NULL; + /* + * Note: it is essential that we don't wait for the buffer to be + * read if dm_bufio_get function is used. Both dm_bufio_get and + * dm_bufio_prefetch can be used in the driver request routine. + * If the user called both dm_bufio_prefetch and dm_bufio_get on + * the same buffer, it would deadlock if we waited. + */ + if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) + return NULL; + + b->hold_count++; + __relink_lru(b, test_bit(B_DIRTY, &b->state) || + test_bit(B_WRITING, &b->state)); + return b; } /* @@ -956,10 +975,10 @@ static void *new_read(struct dm_bufio_client *c, sector_t block, struct dm_buffer *b; dm_bufio_lock(c); - b = __bufio_new(c, block, nf, bp, &need_submit); + b = __bufio_new(c, block, nf, &need_submit); dm_bufio_unlock(c); - if (!b || IS_ERR(b)) + if (!b) return b; if (need_submit) @@ -1005,13 +1024,47 @@ void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, } EXPORT_SYMBOL_GPL(dm_bufio_new); +void dm_bufio_prefetch(struct dm_bufio_client *c, + sector_t block, unsigned n_blocks) +{ + struct blk_plug plug; + + blk_start_plug(&plug); + dm_bufio_lock(c); + + for (; n_blocks--; block++) { + int need_submit; + struct dm_buffer *b; + b = __bufio_new(c, block, NF_PREFETCH, &need_submit); + if (unlikely(b != NULL)) { + dm_bufio_unlock(c); + + if (need_submit) + submit_io(b, READ, b->block, read_endio); + dm_bufio_release(b); + + dm_bufio_cond_resched(); + + if (!n_blocks) + goto flush_plug; + dm_bufio_lock(c); + } + + } + + dm_bufio_unlock(c); + +flush_plug: + blk_finish_plug(&plug); +} +EXPORT_SYMBOL_GPL(dm_bufio_prefetch); + void dm_bufio_release(struct dm_buffer *b) { struct dm_bufio_client *c = b->c; dm_bufio_lock(c); - BUG_ON(test_bit(B_READING, &b->state)); BUG_ON(!b->hold_count); b->hold_count--; @@ -1024,6 +1077,7 @@ void dm_bufio_release(struct dm_buffer *b) * invalid buffer. */ if ((b->read_error || b->write_error) && + !test_bit(B_READING, &b->state) && !test_bit(B_WRITING, &b->state) && !test_bit(B_DIRTY, &b->state)) { __unlink_buffer(b); @@ -1041,6 +1095,8 @@ void dm_bufio_mark_buffer_dirty(struct dm_buffer *b) dm_bufio_lock(c); + BUG_ON(test_bit(B_READING, &b->state)); + if (!test_and_set_bit(B_DIRTY, &b->state)) __relink_lru(b, LIST_DIRTY); diff --git a/drivers/md/dm-bufio.h b/drivers/md/dm-bufio.h index 5c4c3a04e38..b142946a9e3 100644 --- a/drivers/md/dm-bufio.h +++ b/drivers/md/dm-bufio.h @@ -63,6 +63,14 @@ void *dm_bufio_new(struct dm_bufio_client *c, sector_t block, struct dm_buffer **bp); /* + * Prefetch the specified blocks to the cache. + * The function starts to read the blocks and returns without waiting for + * I/O to finish. + */ +void dm_bufio_prefetch(struct dm_bufio_client *c, + sector_t block, unsigned n_blocks); + +/* * Release a reference obtained with dm_bufio_{read,get,new}. The data * pointer and dm_buffer pointer is no longer valid after this call. */ |