On 02/17/12 07:16, Jeff Liu wrote:
Hello,
This is the revised patch according to Dave's comments for V7.
Changes to V8:
--------------
1. If there is an internal error raised at extent reading routine, just
return it rather than ENXIO.
2. Add the commit message.
3. Remove the for(;;) loop since there is no continuous holes shown even
if create a Petabyte sparse file with hole extent length longer than
32-bit. Thanks Dave for helping verify that!
4. In xfs_seek_data(), s/len/end/, looks 'end' is more meaningful here
to indicate the range of extents mapped.
5. Remove BUG() from xfs_seek_data() since xfs_bmapi_read() have found
any corruption during the lookup, it should not occurred at all.
Any comments are appreciated!
Thanks,
-Jeff
Signed-off-by: Jie Liu<jeff.liu@xxxxxxxxxx>
---
This patch adds lseek(2) SEEK_DATA/SEEK_HOLE functionality.
+STATIC loff_t
+xfs_seek_hole(
+ struct file *file,
+ loff_t start,
+ u32 type)
+{
+ struct inode *inode = file->f_mapping->host;
+ 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;
+ uint lock;
+ int error;
+
+ lock = xfs_ilock_map_shared(ip);
+
+ isize = i_size_read(inode);
+ if (start>= isize) {
+ error = ENXIO;
+ goto out_unlock;
+ }
+
+ fsbno = XFS_B_TO_FSBT(mp, start);
+ error = xfs_bmap_first_unused(NULL, ip, 1,&fsbno, XFS_DATA_FORK);
+ if (error)
+ goto out_unlock;
+
+ holeoff = XFS_FSB_TO_B(mp, fsbno);
+ if (holeoff<= start)
+ offset = start;
+ else
+ offset = min_t(loff_t, holeoff, isize);
+
+ if (offset != file->f_pos)
+ file->f_pos = offset;
+
+out_unlock:
+ xfs_iunlock_map_shared(ip, lock);
+
+ if (error)
+ return -error;
+ return offset;
+}
Sorry this got set aside. This is being dusted off for inclusion.
Refresh my memory, do we need a XFS_FORCED_SHUTDOWN test in
xfs_seek_hole()? In the earlier versions it was covered in the
xfs_bmapi_read().
A comment on the min_t() that the xfs_bmap_first_unused() could
return a value bigger than the isize if there are no more holes
may help the forgetful such as myself.
Otherwise it looks good.
Thank-you.
Mark Tinguely <tinguely@xxxxxxx>
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