On 25/03/17 21:24, Theodore Ts'o wrote: > We must lock the xattr block before calculating or verifying the > checksum in order to avoid spurious checksum failures. > > https://bugzilla.kernel.org/show_bug.cgi?id=193661 > > Reported-by: Colin Ian King <colin.king@xxxxxxxxxxxxx> > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > fs/ext4/xattr.c | 65 +++++++++++++++++++++++++++------------------------------ > 1 file changed, 31 insertions(+), 34 deletions(-) > > diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c > index 67636acf7624..996e7900d4c8 100644 > --- a/fs/ext4/xattr.c > +++ b/fs/ext4/xattr.c > @@ -131,31 +131,26 @@ static __le32 ext4_xattr_block_csum(struct inode *inode, > } > > static int ext4_xattr_block_csum_verify(struct inode *inode, > - sector_t block_nr, > - struct ext4_xattr_header *hdr) > + struct buffer_head *bh) > { > - if (ext4_has_metadata_csum(inode->i_sb) && > - (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr))) > - return 0; > - return 1; > -} > - > -static void ext4_xattr_block_csum_set(struct inode *inode, > - sector_t block_nr, > - struct ext4_xattr_header *hdr) > -{ > - if (!ext4_has_metadata_csum(inode->i_sb)) > - return; > + struct ext4_xattr_header *hdr = BHDR(bh); > + int ret = 1; > > - hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr); > + if (ext4_has_metadata_csum(inode->i_sb)) { > + lock_buffer(bh); > + ret = (hdr->h_checksum == ext4_xattr_block_csum(inode, > + bh->b_blocknr, hdr)); > + unlock_buffer(bh); > + } > + return ret; > } > > -static inline int ext4_handle_dirty_xattr_block(handle_t *handle, > - struct inode *inode, > - struct buffer_head *bh) > +static void ext4_xattr_block_csum_set(struct inode *inode, > + struct buffer_head *bh) > { > - ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh)); > - return ext4_handle_dirty_metadata(handle, inode, bh); > + if (ext4_has_metadata_csum(inode->i_sb)) > + BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode, > + bh->b_blocknr, BHDR(bh)); > } > > static inline const struct xattr_handler * > @@ -233,7 +228,7 @@ ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh) > if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || > BHDR(bh)->h_blocks != cpu_to_le32(1)) > return -EFSCORRUPTED; > - if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh))) > + if (!ext4_xattr_block_csum_verify(inode, bh)) > return -EFSBADCRC; > error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size, > bh->b_data); > @@ -618,23 +613,22 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode, > } > } > > + ext4_xattr_block_csum_set(inode, bh); > /* > * Beware of this ugliness: Releasing of xattr block references > * from different inodes can race and so we have to protect > * from a race where someone else frees the block (and releases > * its journal_head) before we are done dirtying the buffer. In > * nojournal mode this race is harmless and we actually cannot > - * call ext4_handle_dirty_xattr_block() with locked buffer as > + * call ext4_handle_dirty_metadata() with locked buffer as > * that function can call sync_dirty_buffer() so for that case > * we handle the dirtying after unlocking the buffer. > */ > if (ext4_handle_valid(handle)) > - error = ext4_handle_dirty_xattr_block(handle, inode, > - bh); > + error = ext4_handle_dirty_metadata(handle, inode, bh); > unlock_buffer(bh); > if (!ext4_handle_valid(handle)) > - error = ext4_handle_dirty_xattr_block(handle, inode, > - bh); > + error = ext4_handle_dirty_metadata(handle, inode, bh); > if (IS_SYNC(inode)) > ext4_handle_sync(handle); > dquot_free_block(inode, EXT4_C2B(EXT4_SB(inode->i_sb), 1)); > @@ -863,13 +857,14 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, > ext4_xattr_cache_insert(ext4_mb_cache, > bs->bh); > } > + ext4_xattr_block_csum_set(inode, bs->bh); > unlock_buffer(bs->bh); > if (error == -EFSCORRUPTED) > goto bad_block; > if (!error) > - error = ext4_handle_dirty_xattr_block(handle, > - inode, > - bs->bh); > + error = ext4_handle_dirty_metadata(handle, > + inode, > + bs->bh); > if (error) > goto cleanup; > goto inserted; > @@ -967,10 +962,11 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, > ce->e_reusable = 0; > ea_bdebug(new_bh, "reusing; refcount now=%d", > ref); > + ext4_xattr_block_csum_set(inode, new_bh); > unlock_buffer(new_bh); > - error = ext4_handle_dirty_xattr_block(handle, > - inode, > - new_bh); > + error = ext4_handle_dirty_metadata(handle, > + inode, > + new_bh); > if (error) > goto cleanup_dquot; > } > @@ -1020,11 +1016,12 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, > goto getblk_failed; > } > memcpy(new_bh->b_data, s->base, new_bh->b_size); > + ext4_xattr_block_csum_set(inode, new_bh); > set_buffer_uptodate(new_bh); > unlock_buffer(new_bh); > ext4_xattr_cache_insert(ext4_mb_cache, new_bh); > - error = ext4_handle_dirty_xattr_block(handle, > - inode, new_bh); > + error = ext4_handle_dirty_metadata(handle, inode, > + new_bh); > if (error) > goto cleanup; > } > I've given this a good soak test on 32 bit and 64 bit x86 builds and it fixes the issue. Thanks Ted. Tested-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>