diff options
| -rw-r--r-- | fs/xfs/xfs_iomap.c | 46 |
1 files changed, 25 insertions, 21 deletions
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 2ace8b8ffc86..df1eab646cae 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -1830,14 +1830,29 @@ restart: goto out_unlock; /* - * Search the data fork first to look up our source mapping. We - * always need the data fork map, as we have to return it to the - * iomap code so that the higher level write code can read data in to - * perform read-modify-write cycles for unaligned writes. + * Search the data fork first to look up our source mapping. We always + * need the data fork map, as we have to return it to the iomap code so + * that the higher level write code can read data in to perform + * read-modify-write cycles for unaligned writes. + * + * Then search the COW fork extent list even if we did not find a data + * fork extent. This serves two purposes: first this implements the + * speculative preallocation using cowextsize, so that we also unshare + * block adjacent to shared blocks instead of just the shared blocks + * themselves. Second the lookup in the extent list is generally faster + * than going out to the shared extent tree. */ eof = !xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap); if (eof) imap.br_startoff = end_fsb; /* fake hole until the end */ + if (xfs_is_cow_inode(ip)) { + if (!ip->i_cowfp) { + ASSERT(!xfs_is_reflink_inode(ip)); + xfs_ifork_init_cow(ip); + } + cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, + &ccur, &cmap); + } /* We never need to allocate blocks for unsharing a hole. */ if ((flags & IOMAP_UNSHARE) && imap.br_startoff > offset_fsb) { @@ -1904,24 +1919,13 @@ restart: } /* - * Search the COW fork extent list even if we did not find a data fork - * extent. This serves two purposes: first this implements the - * speculative preallocation using cowextsize, so that we also unshare - * block adjacent to shared blocks instead of just the shared blocks - * themselves. Second the lookup in the extent list is generally faster - * than going out to the shared extent tree. + * Now that we've handled any operation specific special cases, at this + * point we can report a COW mapping if found. */ - if (xfs_is_cow_inode(ip)) { - if (!ip->i_cowfp) { - ASSERT(!xfs_is_reflink_inode(ip)); - xfs_ifork_init_cow(ip); - } - cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, - &ccur, &cmap); - if (!cow_eof && cmap.br_startoff <= offset_fsb) { - trace_xfs_reflink_cow_found(ip, &cmap); - goto found_cow; - } + if (xfs_is_cow_inode(ip) && + !cow_eof && cmap.br_startoff <= offset_fsb) { + trace_xfs_reflink_cow_found(ip, &cmap); + goto found_cow; } if (imap.br_startoff <= offset_fsb) { |