[PATCH 5.17 0883/1126] btrfs: do not double complete bio on errors during compressed reads

Greg Kroah-Hartman
2022-04-05T09:08:30Z

From: Josef Bacik <josef@toxicpanda.com>

[ Upstream commit f9f15de85d74e7eef021af059ca53a15f041cdd8 ]

I hit some weird panics while fixing up the error handling from
btrfs_lookup_bio_sums(). Turns out the compression path will complete
the bio we use if we set up any of the compression bios and then return
an error, and then btrfs_submit_data_bio() will also call bio_endio() on
the bio.

Fix this by making btrfs_submit_compressed_read() responsible for
calling bio_endio() on the bio if there are any errors. Currently it
was only doing it if we created the compression bios, otherwise it was
depending on btrfs_submit_data_bio() to do the right thing. This
creates the above problem, so fix up btrfs_submit_compressed_read() to
always call bio_endio() in case of an error, and then simply return from
btrfs_submit_data_bio() if we had to call
btrfs_submit_compressed_read().

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/compression.c | 20 ++++++++++++++------
fs/btrfs/inode.c | 8 +++++++-
2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 71e5b2e9a1ba..6158b870a269 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -808,7 +808,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
u64 em_len;
u64 em_start;
struct extent_map *em;
- blk_status_t ret = BLK_STS_RESOURCE;
+ blk_status_t ret;
int faili = 0;
u8 *sums;

@@ -821,14 +821,18 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, file_offset, fs_info->sectorsize);
read_unlock(&em_tree->lock);
- if (!em)
- return BLK_STS_IOERR;
+ if (!em) {
+ ret = BLK_STS_IOERR;
+ goto out;
+ }

ASSERT(em->compress_type != BTRFS_COMPRESS_NONE);
compressed_len = em->block_len;
cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
- if (!cb)
+ if (!cb) {
+ ret = BLK_STS_RESOURCE;
goto out;
+ }

refcount_set(&cb->pending_sectors, compressed_len >> fs_info->sectorsize_bits);
cb->errors = 0;
@@ -851,8 +855,10 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
GFP_NOFS);
- if (!cb->compressed_pages)
+ if (!cb->compressed_pages) {
+ ret = BLK_STS_RESOURCE;
goto fail1;
+ }

for (pg_index = 0; pg_index < nr_pages; pg_index++) {
cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS);
@@ -938,7 +944,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
comp_bio = NULL;
}
}
- return 0;
+ return BLK_STS_OK;

fail2:
while (faili >= 0) {
@@ -951,6 +957,8 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
kfree(cb);
out:
free_extent_map(em);
+ bio->bi_status = ret;
+ bio_endio(bio);
return ret;
finish_cb:
if (comp_bio) {
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5bbea5ec31fc..0f4408f9dadd 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2538,10 +2538,15 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
goto out;

if (bio_flags & EXTENT_BIO_COMPRESSED) {
+ /*
+ * btrfs_submit_compressed_read will handle completing
+ * the bio if there were any errors, so just return
+ * here.
+ */
ret = btrfs_submit_compressed_read(inode, bio,
mirror_num,
bio_flags);
- goto out;
+ goto out_no_endio;
} else {
/*
* Lookup bio sums does extra checks around whether we
@@ -2575,6 +2580,7 @@ blk_status_t btrfs_submit_data_bio(struct inode *inode, struct bio *bio,
bio->bi_status = ret;
bio_endio(bio);
}
+out_no_endio:
return ret;
}

--
2.34.1