diff options
| -rw-r--r-- | fs/btrfs/extent_io.c | 135 |
1 files changed, 106 insertions, 29 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index a50adbd8808d..8c006a182d6b 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4080,13 +4080,98 @@ static void set_btree_ioerr(struct page *page, struct extent_buffer *eb) } } +/* + * The endio specific version which won't touch any unsafe spinlock in endio + * context. + */ +static struct extent_buffer *find_extent_buffer_nolock( + struct btrfs_fs_info *fs_info, u64 start) +{ + struct extent_buffer *eb; + + rcu_read_lock(); + eb = radix_tree_lookup(&fs_info->buffer_radix, + start >> fs_info->sectorsize_bits); + if (eb && atomic_inc_not_zero(&eb->refs)) { + rcu_read_unlock(); + return eb; + } + rcu_read_unlock(); + return NULL; +} + +/* + * The endio function for subpage extent buffer write. + * + * Unlike end_bio_extent_buffer_writepage(), we only call end_page_writeback() + * after all extent buffers in the page has finished their writeback. + */ +static void end_bio_subpage_eb_writepage(struct btrfs_fs_info *fs_info, + struct bio *bio) +{ + struct bio_vec *bvec; + struct bvec_iter_all iter_all; + + ASSERT(!bio_flagged(bio, BIO_CLONED)); + bio_for_each_segment_all(bvec, bio, iter_all) { + struct page *page = bvec->bv_page; + u64 bvec_start = page_offset(page) + bvec->bv_offset; + u64 bvec_end = bvec_start + bvec->bv_len - 1; + u64 cur_bytenr = bvec_start; + + ASSERT(IS_ALIGNED(bvec->bv_len, fs_info->nodesize)); + + /* Iterate through all extent buffers in the range */ + while (cur_bytenr <= bvec_end) { + struct extent_buffer *eb; + int done; + + /* + * Here we can't use find_extent_buffer(), as it may + * try to lock eb->refs_lock, which is not safe in endio + * context. + */ + eb = find_extent_buffer_nolock(fs_info, cur_bytenr); + ASSERT(eb); + + cur_bytenr = eb->start + eb->len; + + ASSERT(test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)); + done = atomic_dec_and_test(&eb->io_pages); + ASSERT(done); + + if (bio->bi_status || + test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)) { + ClearPageUptodate(page); + set_btree_ioerr(page, eb); + } + + btrfs_subpage_clear_writeback(fs_info, page, eb->start, + eb->len); + end_extent_buffer_writeback(eb); + /* + * free_extent_buffer() will grab spinlock which is not + * safe in endio context. Thus here we manually dec + * the ref. + */ + atomic_dec(&eb->refs); + } + } + bio_put(bio); +} + static void end_bio_extent_buffer_writepage(struct bio *bio) { + struct btrfs_fs_info *fs_info; struct bio_vec *bvec; struct extent_buffer *eb; int done; struct bvec_iter_all iter_all; + fs_info = btrfs_sb(bio_first_page_all(bio)->mapping->host->i_sb); + if (fs_info->sectorsize < PAGE_SIZE) + return end_bio_subpage_eb_writepage(fs_info, bio); + ASSERT(!bio_flagged(bio, BIO_CLONED)); bio_for_each_segment_all(bvec, bio, iter_all) { struct page *page = bvec->bv_page; @@ -5465,36 +5550,28 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info, { struct extent_buffer *eb; - rcu_read_lock(); - eb = radix_tree_lookup(&fs_info->buffer_radix, - start >> fs_info->sectorsize_bits); - if (eb && atomic_inc_not_zero(&eb->refs)) { - rcu_read_unlock(); - /* - * Lock our eb's refs_lock to avoid races with - * free_extent_buffer. When we get our eb it might be flagged - * with EXTENT_BUFFER_STALE and another task running - * free_extent_buffer might have seen that flag set, - * eb->refs == 2, that the buffer isn't under IO (dirty and - * writeback flags not set) and it's still in the tree (flag - * EXTENT_BUFFER_TREE_REF set), therefore being in the process - * of decrementing the extent buffer's reference count twice. - * So here we could race and increment the eb's reference count, - * clear its stale flag, mark it as dirty and drop our reference - * before the other task finishes executing free_extent_buffer, - * which would later result in an attempt to free an extent - * buffer that is dirty. - */ - if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) { - spin_lock(&eb->refs_lock); - spin_unlock(&eb->refs_lock); - } - mark_extent_buffer_accessed(eb, NULL); - return eb; + eb = find_extent_buffer_nolock(fs_info, start); + if (!eb) + return NULL; + /* + * Lock our eb's refs_lock to avoid races with free_extent_buffer(). + * When we get our eb it might be flagged with EXTENT_BUFFER_STALE and + * another task running free_extent_buffer() might have seen that flag + * set, eb->refs == 2, that the buffer isn't under IO (dirty and + * writeback flags not set) and it's still in the tree (flag + * EXTENT_BUFFER_TREE_REF set), therefore being in the process of + * decrementing the extent buffer's reference count twice. So here we + * could race and increment the eb's reference count, clear its stale + * flag, mark it as dirty and drop our reference before the other task + * finishes executing free_extent_buffer, which would later result in + * an attempt to free an extent buffer that is dirty. + */ + if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) { + spin_lock(&eb->refs_lock); + spin_unlock(&eb->refs_lock); } - rcu_read_unlock(); - - return NULL; + mark_extent_buffer_accessed(eb, NULL); + return eb; } #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS |