diff options
| -rw-r--r-- | fs/xfs/xfs_reflink.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 59da9708e9c1..f889398e25d6 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1265,6 +1265,19 @@ xfs_reflink_zero_posteof( * will have the iolock and mmaplock held, the page cache of the out file * will be truncated, and any leases on the out file will have been broken. * This function borrows heavily from xfs_file_aio_write_checks. + * + * The VFS allows partial EOF blocks to "match" for dedupe even though it hasn't + * checked that the bytes beyond EOF physically match. Hence we cannot use the + * EOF block in the source dedupe range because it's not a complete block match, + * hence can introduce a corruption into the file that has it's + * block replaced. + * + * Despite this issue, we still need to report that range as successfully + * deduped to avoid confusing userspace with EINVAL errors on completely + * matching file data. The only time that an unaligned length will be passed to + * us is when it spans the EOF block of the source file, so if we simply mask it + * down to be block aligned here the we will dedupe everything but that partial + * EOF block. */ STATIC int xfs_reflink_remap_prep( @@ -1307,6 +1320,14 @@ xfs_reflink_remap_prep( if (ret <= 0) goto out_unlock; + /* + * If the dedupe data matches, chop off the partial EOF block + * from the source file so we don't try to dedupe the partial + * EOF block. + */ + if (is_dedupe) + *len &= ~((u64)i_blocksize(inode_in) - 1); + /* Attach dquots to dest inode before changing block map */ ret = xfs_qm_dqattach(dest); if (ret) |