From cc05d22c04507440c644384d3b68def65653b0de Mon Sep 17 00:00:00 2001 Message-Id: From: Qu Wenruo Date: Wed, 28 Dec 2022 08:44:18 +0800 Subject: [PATCH] btrfs: fix the false alert on bad tree level [BUG] There is a bug report that on a RAID0 nvme btrfs system, under heavy write load the fs can flip RO randomly. With extra debug, it shows some tree blocks failed to pass its level checks, and if that happens at critical path of a transaction, we abort the transacation: BTRFS error (device nvme0n1p3): level verify failed on logical 5446121209856 mirror 1 wanted 0 found 1 BTRFS error (device nvme0n1p3: state A): Transaction aborted (error -5) BTRFS: error (device nvme0n1p3: state A) in btrfs_finish_ordered_io:3343: errno=-5 IO failure BTRFS info (device nvme0n1p3: state EA): forced readonly [CAUSE] The reporter has already bisected to commit 947a629988f1 ("btrfs: move tree block parentness check into validate_extent_buffer()"). And with extra debug, it shows we can have btrfs_tree_parent_check filled with all zero in the following call trace: submit_one_bio+0xd4/0xe0 submit_extent_page+0x142/0x550 read_extent_buffer_pages+0x584/0x9c0 ? __pfx_end_bio_extent_readpage+0x10/0x10 ? folio_unlock+0x1d/0x50 btrfs_read_extent_buffer+0x98/0x150 read_tree_block+0x43/0xa0 read_block_for_search+0x266/0x370 btrfs_search_slot+0x351/0xd30 ? lock_is_held_type+0xe8/0x140 btrfs_lookup_csum+0x63/0x150 btrfs_csum_file_blocks+0x197/0x6c0 ? sched_clock_cpu+0x9f/0xc0 ? lock_release+0x14b/0x440 ? _raw_read_unlock+0x29/0x50 btrfs_finish_ordered_io+0x441/0x860 btrfs_work_helper+0xfe/0x400 ? lock_is_held_type+0xe8/0x140 process_one_work+0x294/0x5b0 worker_thread+0x4f/0x3a0 ? __pfx_worker_thread+0x10/0x10 kthread+0xf5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 Currently we only copy the btrfs_tree_parent_check structure into bbio at read_extent_buffer_pages() after we have assembled the bbio. But as shown in the above call trace, submit_extent_page() itself can already submit the bbio, leaving the bbio->parent_check uninitialized, and cause the false alert. [FIX] Instead of copying @check into bbio after bbio is assembled, we pass @check in btrfs_bio_ctrl::parent_check, and copy the content of parent_check in submit_one_bio() for metadata read. By this, we should be able to pass the needed info for metadata endio verification, and fix the false alert. Reported-by: Mikhail Gavrilov Link: Mikhail Gavrilov Fixes: 947a629988f1 ("btrfs: move tree block parentness check into validate_extent_buffer()") Signed-off-by: Qu Wenruo --- fs/btrfs/extent_io.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 83dd3aa59663..b11332482d57 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -103,6 +103,16 @@ struct btrfs_bio_ctrl { u32 len_to_oe_boundary; btrfs_bio_end_io_t end_io_func; + /* + * This is for metadata read, to provide the extra needed + * verification info. + * This has to be provided for submit_one_bio(), as submit_one_bio() + * can submit a bio if it ends at stripe boundary. + * If no such parent_check provided, the metadata can hit false alert + * at endio time. + */ + struct btrfs_tree_parent_check *parent_check; + /* * Tell writepage not to lock the state bits for this range, it still * does the unlocking. @@ -133,13 +143,24 @@ static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl) btrfs_bio(bio)->file_offset = page_offset(bv->bv_page) + bv->bv_offset; - if (!is_data_inode(&inode->vfs_inode)) + if (!is_data_inode(&inode->vfs_inode)) { + if (btrfs_op(bio) != BTRFS_MAP_WRITE) { + /* + * For metadata read, we should have the parent_check, + * and copy it to bbio for metadata verification. + */ + ASSERT(bio_ctrl->parent_check); + memcpy(&btrfs_bio(bio)->parent_check, + bio_ctrl->parent_check, + sizeof(struct btrfs_tree_parent_check)); + } btrfs_submit_metadata_bio(inode, bio, mirror_num); - else if (btrfs_op(bio) == BTRFS_MAP_WRITE) + } else if (btrfs_op(bio) == BTRFS_MAP_WRITE) { btrfs_submit_data_write_bio(inode, bio, mirror_num); - else + } else { btrfs_submit_data_read_bio(inode, bio, mirror_num, bio_ctrl->compress_type); + } /* The bio is owned by the end_io handler now */ bio_ctrl->bio = NULL; @@ -4829,6 +4850,7 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait, struct extent_state *cached_state = NULL; struct btrfs_bio_ctrl bio_ctrl = { .mirror_num = mirror_num, + .parent_check = check, }; int ret = 0; @@ -4878,7 +4900,6 @@ static int read_extent_buffer_subpage(struct extent_buffer *eb, int wait, */ atomic_dec(&eb->io_pages); } - memcpy(&btrfs_bio(bio_ctrl.bio)->parent_check, check, sizeof(*check)); submit_one_bio(&bio_ctrl); if (ret || wait != WAIT_COMPLETE) { free_extent_state(cached_state); @@ -4905,6 +4926,7 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num, unsigned long num_reads = 0; struct btrfs_bio_ctrl bio_ctrl = { .mirror_num = mirror_num, + .parent_check = check, }; if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) @@ -4996,7 +5018,6 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num, } } - memcpy(&btrfs_bio(bio_ctrl.bio)->parent_check, check, sizeof(*check)); submit_one_bio(&bio_ctrl); if (ret || wait != WAIT_COMPLETE) -- 2.39.0