diff options
| -rw-r--r-- | fs/buffer.c | 73 | ||||
| -rw-r--r-- | fs/ext4/ialloc.c | 3 | ||||
| -rw-r--r-- | fs/ext4/mballoc.c | 3 | ||||
| -rw-r--r-- | fs/jbd2/revoke.c | 15 | ||||
| -rw-r--r-- | fs/ocfs2/journal.c | 2 | ||||
| -rw-r--r-- | include/linux/buffer_head.h | 9 | ||||
| -rw-r--r-- | mm/migrate.c | 8 |
7 files changed, 82 insertions, 31 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index c7abb4a029dc..7be23ff20b27 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -176,18 +176,8 @@ void end_buffer_write_sync(struct buffer_head *bh, int uptodate) } EXPORT_SYMBOL(end_buffer_write_sync); -/* - * Various filesystems appear to want __find_get_block to be non-blocking. - * But it's the page lock which protects the buffers. To get around this, - * we get exclusion from try_to_free_buffers with the blockdev mapping's - * i_private_lock. - * - * Hack idea: for the blockdev mapping, i_private_lock contention - * may be quite high. This code could TryLock the page, and if that - * succeeds, there is no need to take i_private_lock. - */ static struct buffer_head * -__find_get_block_slow(struct block_device *bdev, sector_t block) +__find_get_block_slow(struct block_device *bdev, sector_t block, bool atomic) { struct address_space *bd_mapping = bdev->bd_mapping; const int blkbits = bd_mapping->host->i_blkbits; @@ -204,10 +194,28 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) if (IS_ERR(folio)) goto out; - spin_lock(&bd_mapping->i_private_lock); + /* + * Folio lock protects the buffers. Callers that cannot block + * will fallback to serializing vs try_to_free_buffers() via + * the i_private_lock. + */ + if (atomic) + spin_lock(&bd_mapping->i_private_lock); + else + folio_lock(folio); + head = folio_buffers(folio); if (!head) goto out_unlock; + /* + * Upon a noref migration, the folio lock serializes here; + * otherwise bail. + */ + if (test_bit_acquire(BH_Migrate, &head->b_state)) { + WARN_ON(!atomic); + goto out_unlock; + } + bh = head; do { if (!buffer_mapped(bh)) @@ -236,7 +244,10 @@ __find_get_block_slow(struct block_device *bdev, sector_t block) 1 << blkbits); } out_unlock: - spin_unlock(&bd_mapping->i_private_lock); + if (atomic) + spin_unlock(&bd_mapping->i_private_lock); + else + folio_unlock(folio); folio_put(folio); out: return ret; @@ -656,7 +667,9 @@ EXPORT_SYMBOL(generic_buffers_fsync); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize) { - struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); + struct buffer_head *bh; + + bh = __find_get_block_nonatomic(bdev, bblock + 1, blocksize); if (bh) { if (buffer_dirty(bh)) write_dirty_buffer(bh, 0); @@ -1386,16 +1399,18 @@ lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) /* * Perform a pagecache lookup for the matching buffer. If it's there, refresh * it in the LRU and mark it as accessed. If it is not present then return - * NULL + * NULL. Atomic context callers may also return NULL if the buffer is being + * migrated; similarly the page is not marked accessed either. */ -struct buffer_head * -__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +static struct buffer_head * +find_get_block_common(struct block_device *bdev, sector_t block, + unsigned size, bool atomic) { struct buffer_head *bh = lookup_bh_lru(bdev, block, size); if (bh == NULL) { /* __find_get_block_slow will mark the page accessed */ - bh = __find_get_block_slow(bdev, block); + bh = __find_get_block_slow(bdev, block, atomic); if (bh) bh_lru_install(bh); } else @@ -1403,8 +1418,23 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size) return bh; } + +struct buffer_head * +__find_get_block(struct block_device *bdev, sector_t block, unsigned size) +{ + return find_get_block_common(bdev, block, size, true); +} EXPORT_SYMBOL(__find_get_block); +/* same as __find_get_block() but allows sleeping contexts */ +struct buffer_head * +__find_get_block_nonatomic(struct block_device *bdev, sector_t block, + unsigned size) +{ + return find_get_block_common(bdev, block, size, false); +} +EXPORT_SYMBOL(__find_get_block_nonatomic); + /** * bdev_getblk - Get a buffer_head in a block device's buffer cache. * @bdev: The block device. @@ -1422,7 +1452,12 @@ EXPORT_SYMBOL(__find_get_block); struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block, unsigned size, gfp_t gfp) { - struct buffer_head *bh = __find_get_block(bdev, block, size); + struct buffer_head *bh; + + if (gfpflags_allow_blocking(gfp)) + bh = __find_get_block_nonatomic(bdev, block, size); + else + bh = __find_get_block(bdev, block, size); might_alloc(gfp); if (bh) diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c index 38bc8d74f4cc..e7ecc7c8a729 100644 --- a/fs/ext4/ialloc.c +++ b/fs/ext4/ialloc.c @@ -691,7 +691,8 @@ static int recently_deleted(struct super_block *sb, ext4_group_t group, int ino) if (!bh || !buffer_uptodate(bh)) /* * If the block is not in the buffer cache, then it - * must have been written out. + * must have been written out, or, most unlikely, is + * being migrated - false failure should be OK here. */ goto out; diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index f88424c28194..1e98c5be4e0a 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -6642,7 +6642,8 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode, for (i = 0; i < count; i++) { cond_resched(); if (is_metadata) - bh = sb_find_get_block(inode->i_sb, block + i); + bh = sb_find_get_block_nonatomic(inode->i_sb, + block + i); ext4_forget(handle, is_metadata, inode, bh, block + i); } } diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c index 0cf0fddbee81..1467f6790747 100644 --- a/fs/jbd2/revoke.c +++ b/fs/jbd2/revoke.c @@ -345,7 +345,8 @@ int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr, bh = bh_in; if (!bh) { - bh = __find_get_block(bdev, blocknr, journal->j_blocksize); + bh = __find_get_block_nonatomic(bdev, blocknr, + journal->j_blocksize); if (bh) BUFFER_TRACE(bh, "found on hash"); } @@ -355,7 +356,8 @@ int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr, /* If there is a different buffer_head lying around in * memory anywhere... */ - bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize); + bh2 = __find_get_block_nonatomic(bdev, blocknr, + journal->j_blocksize); if (bh2) { /* ... and it has RevokeValid status... */ if (bh2 != bh && buffer_revokevalid(bh2)) @@ -464,7 +466,8 @@ void jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh) * state machine will get very upset later on. */ if (need_cancel) { struct buffer_head *bh2; - bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size); + bh2 = __find_get_block_nonatomic(bh->b_bdev, bh->b_blocknr, + bh->b_size); if (bh2) { if (bh2 != bh) clear_buffer_revoked(bh2); @@ -492,9 +495,9 @@ void jbd2_clear_buffer_revoked_flags(journal_t *journal) struct jbd2_revoke_record_s *record; struct buffer_head *bh; record = (struct jbd2_revoke_record_s *)list_entry; - bh = __find_get_block(journal->j_fs_dev, - record->blocknr, - journal->j_blocksize); + bh = __find_get_block_nonatomic(journal->j_fs_dev, + record->blocknr, + journal->j_blocksize); if (bh) { clear_buffer_revoked(bh); __brelse(bh); diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c index f1b4b3e611cb..c7a9729dc9d0 100644 --- a/fs/ocfs2/journal.c +++ b/fs/ocfs2/journal.c @@ -1249,7 +1249,7 @@ static int ocfs2_force_read_journal(struct inode *inode) } for (i = 0; i < p_blocks; i++, p_blkno++) { - bh = __find_get_block(osb->sb->s_bdev, p_blkno, + bh = __find_get_block_nonatomic(osb->sb->s_bdev, p_blkno, osb->sb->s_blocksize); /* block not cached. */ if (!bh) diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index f0a4ad7839b6..0029ff880e27 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -34,6 +34,7 @@ enum bh_state_bits { BH_Meta, /* Buffer contains metadata */ BH_Prio, /* Buffer should be submitted with REQ_PRIO */ BH_Defer_Completion, /* Defer AIO completion to workqueue */ + BH_Migrate, /* Buffer is being migrated (norefs) */ BH_PrivateStart,/* not a state bit, but the first bit available * for private allocation by other entities @@ -222,6 +223,8 @@ void __wait_on_buffer(struct buffer_head *); wait_queue_head_t *bh_waitq_head(struct buffer_head *bh); struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block, unsigned size); +struct buffer_head *__find_get_block_nonatomic(struct block_device *bdev, + sector_t block, unsigned size); struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block, unsigned size, gfp_t gfp); void __brelse(struct buffer_head *); @@ -397,6 +400,12 @@ sb_find_get_block(struct super_block *sb, sector_t block) return __find_get_block(sb->s_bdev, block, sb->s_blocksize); } +static inline struct buffer_head * +sb_find_get_block_nonatomic(struct super_block *sb, sector_t block) +{ + return __find_get_block_nonatomic(sb->s_bdev, block, sb->s_blocksize); +} + static inline void map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block) { diff --git a/mm/migrate.c b/mm/migrate.c index f3ee6d8d5e2e..676d9cfc7059 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -845,9 +845,11 @@ static int __buffer_migrate_folio(struct address_space *mapping, return -EAGAIN; if (check_refs) { - bool busy; + bool busy, migrating; bool invalidated = false; + migrating = test_and_set_bit_lock(BH_Migrate, &head->b_state); + VM_WARN_ON_ONCE(migrating); recheck_buffers: busy = false; spin_lock(&mapping->i_private_lock); @@ -859,12 +861,12 @@ recheck_buffers: } bh = bh->b_this_page; } while (bh != head); + spin_unlock(&mapping->i_private_lock); if (busy) { if (invalidated) { rc = -EAGAIN; goto unlock_buffers; } - spin_unlock(&mapping->i_private_lock); invalidate_bh_lrus(); invalidated = true; goto recheck_buffers; @@ -883,7 +885,7 @@ recheck_buffers: unlock_buffers: if (check_refs) - spin_unlock(&mapping->i_private_lock); + clear_bit_unlock(BH_Migrate, &head->b_state); bh = head; do { unlock_buffer(bh); |