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author | Jeff Liu <jeff.liu@oracle.com> | 2012-08-21 17:12:18 +0800 |
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committer | Ben Myers <bpm@sgi.com> | 2012-08-24 13:57:10 -0500 |
commit | b686d1f79acb65c6a34473c15fcfa2ee54aed8e2 (patch) | |
tree | bd3e600ce359833dec65b9d64f29e7ce4c54ce87 /fs | |
parent | 52f1acc8b56a333fbc7218711c3fa2fb3bf78b92 (diff) | |
download | linux-stable-b686d1f79acb65c6a34473c15fcfa2ee54aed8e2.tar.gz linux-stable-b686d1f79acb65c6a34473c15fcfa2ee54aed8e2.tar.bz2 linux-stable-b686d1f79acb65c6a34473c15fcfa2ee54aed8e2.zip |
xfs: xfs_seek_hole() refinement with hole searching from page cache for unwritten extents
xfs_seek_hole() refinement with hole searching from page cache for unwritten extent.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/xfs/xfs_file.c | 78 |
1 files changed, 67 insertions, 11 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 3f9107431dfb..1eaeb8be3aae 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1289,9 +1289,9 @@ xfs_seek_hole( struct xfs_inode *ip = XFS_I(inode); struct xfs_mount *mp = ip->i_mount; loff_t uninitialized_var(offset); - loff_t holeoff; xfs_fsize_t isize; xfs_fileoff_t fsbno; + xfs_filblks_t end; uint lock; int error; @@ -1307,21 +1307,77 @@ xfs_seek_hole( } fsbno = XFS_B_TO_FSBT(mp, start); - error = xfs_bmap_first_unused(NULL, ip, 1, &fsbno, XFS_DATA_FORK); - if (error) - goto out_unlock; + end = XFS_B_TO_FSB(mp, isize); + + for (;;) { + struct xfs_bmbt_irec map[2]; + int nmap = 2; + unsigned int i; + + error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap, + XFS_BMAPI_ENTIRE); + if (error) + goto out_unlock; + + /* No extents at given offset, must be beyond EOF */ + if (nmap == 0) { + error = ENXIO; + goto out_unlock; + } + + for (i = 0; i < nmap; i++) { + offset = max_t(loff_t, start, + XFS_FSB_TO_B(mp, map[i].br_startoff)); + + /* Landed in a hole */ + if (map[i].br_startblock == HOLESTARTBLOCK) + goto out; + + /* + * Landed in an unwritten extent, try to search hole + * from page cache. + */ + if (map[i].br_state == XFS_EXT_UNWRITTEN) { + if (xfs_find_get_desired_pgoff(inode, &map[i], + HOLE_OFF, &offset)) + goto out; + } + } - holeoff = XFS_FSB_TO_B(mp, fsbno); - if (holeoff <= start) - offset = start; - else { /* - * xfs_bmap_first_unused() could return a value bigger than - * isize if there are no more holes past the supplied offset. + * map[0] contains data or its unwritten but contains + * data in page cache, probably means that we are + * reading after EOF. We should fix offset to point + * to the end of the file(i.e., there is an implicit + * hole at the end of any file). */ - offset = min_t(loff_t, holeoff, isize); + if (nmap == 1) { + offset = isize; + break; + } + + ASSERT(i > 1); + + /* + * Both mappings contains data, proceed to the next round of + * search if the current reading offset not beyond or hit EOF. + */ + fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount; + start = XFS_FSB_TO_B(mp, fsbno); + if (start >= isize) { + offset = isize; + break; + } } +out: + /* + * At this point, we must have found a hole. However, the returned + * offset may be bigger than the file size as it may be aligned to + * page boundary for unwritten extents, we need to deal with this + * situation in particular. + */ + offset = min_t(loff_t, offset, isize); if (offset != file->f_pos) file->f_pos = offset; |