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btrfs: handle csum lookup errors properly on reads

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Currently any error we get while trying to lookup csums during reads
shows up as a missing csum, and then on the read completion side we
print an error saying there was a csum mismatch and we increase the
device corruption count.

However we could have gotten an EIO from the lookup.  We could also be
inside of a memory constrained container and gotten a ENOMEM while
trying to do the read.  In either case we don't want to make this look
like a file system corruption problem, we want to make it look like the
actual error it is.  Capture any negative value, convert it to the
appropriate blk_status_t, free the csum array if we have one and bail.

Note: a possible improvement would be to make the relocation code look
up the owning inode and see if it's marked as NODATASUM and set
EXTENT_NODATASUM there, that way if there's corruption and there isn't a
checksum when we want it we can fail here rather than later.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2022-02-18 10:03:23 -05:00 committed by David Sterba
parent 03ddb19d2e
commit 1784b7d502
1 changed files with 22 additions and 14 deletions
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36
fs/btrfs/file-item.c
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@ -368,6 +368,7 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
struct btrfs_bio *bbio = NULL;
struct btrfs_path *path;
const u32 sectorsize = fs_info->sectorsize;
const u32 csum_size = fs_info->csum_size;
@ -377,6 +378,7 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
u8 *csum;
const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
int count = 0;
blk_status_t ret = BLK_STS_OK;
if ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
@ -400,7 +402,7 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
return BLK_STS_RESOURCE;
if (!dst) {
struct btrfs_bio *bbio = btrfs_bio(bio);
bbio = btrfs_bio(bio);
if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
@ -456,21 +458,27 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
count = search_csum_tree(fs_info, path, cur_disk_bytenr,
search_len, csum_dst);
if (count <= 0) {
/*
* Either we hit a critical error or we didn't find
* the csum.
* Either way, we put zero into the csums dst, and skip
* to the next sector.
*/
if (count < 0) {
ret = errno_to_blk_status(count);
if (bbio)
btrfs_bio_free_csum(bbio);
break;
}
/*
* We didn't find a csum for this range. We need to make sure
* we complain loudly about this, because we are not NODATASUM.
*
* However for the DATA_RELOC inode we could potentially be
* relocating data extents for a NODATASUM inode, so the inode
* itself won't be marked with NODATASUM, but the extent we're
* copying is in fact NODATASUM. If we don't find a csum we
* assume this is the case.
*/
if (count == 0) {
memset(csum_dst, 0, csum_size);
count = 1;
/*
* For data reloc inode, we need to mark the range
* NODATASUM so that balance won't report false csum
* error.
*/
if (BTRFS_I(inode)->root->root_key.objectid ==
BTRFS_DATA_RELOC_TREE_OBJECTID) {
u64 file_offset;
@ -491,7 +499,7 @@ blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst
}
btrfs_free_path(path);
return BLK_STS_OK;
return ret;
}
int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,