xfs: introduce SEEK_DATA/SEEK_HOLE support
This patch adds lseek(2) SEEK_DATA/SEEK_HOLE functionality to xfs.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 51fc2cf..8d214b8 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -963,8 +963,149 @@
return block_page_mkwrite(vma, vmf, xfs_get_blocks);
}
+STATIC loff_t
+xfs_seek_data(
+ 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;
+ struct xfs_bmbt_irec map[2];
+ int nmap = 2;
+ loff_t uninitialized_var(offset);
+ xfs_fsize_t isize;
+ xfs_fileoff_t fsbno;
+ xfs_filblks_t end;
+ 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);
+
+ /*
+ * Try to read extents from the first block indicated
+ * by fsbno to the end block of the file.
+ */
+ end = XFS_B_TO_FSB(mp, isize);
+
+ error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
+ XFS_BMAPI_ENTIRE);
+ if (error)
+ goto out_unlock;
+
+ /*
+ * Treat unwritten extent as data extent since it might
+ * contains dirty data in page cache.
+ */
+ if (map[0].br_startblock != HOLESTARTBLOCK) {
+ offset = max_t(loff_t, start,
+ XFS_FSB_TO_B(mp, map[0].br_startoff));
+ } else {
+ if (nmap == 1) {
+ error = ENXIO;
+ goto out_unlock;
+ }
+
+ offset = max_t(loff_t, start,
+ XFS_FSB_TO_B(mp, map[1].br_startoff));
+ }
+
+ if (offset != file->f_pos)
+ file->f_pos = offset;
+
+out_unlock:
+ xfs_iunlock_map_shared(ip, lock);
+
+ if (error)
+ return -error;
+ return offset;
+}
+
+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;
+
+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -XFS_ERROR(EIO);
+
+ 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 {
+ /*
+ * xfs_bmap_first_unused() could return a value bigger than
+ * isize if there are no more holes past the supplied offset.
+ */
+ 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;
+}
+
+STATIC loff_t
+xfs_file_llseek(
+ struct file *file,
+ loff_t offset,
+ int origin)
+{
+ switch (origin) {
+ case SEEK_END:
+ case SEEK_CUR:
+ case SEEK_SET:
+ return generic_file_llseek(file, offset, origin);
+ case SEEK_DATA:
+ return xfs_seek_data(file, offset, origin);
+ case SEEK_HOLE:
+ return xfs_seek_hole(file, offset, origin);
+ default:
+ return -EINVAL;
+ }
+}
+
const struct file_operations xfs_file_operations = {
- .llseek = generic_file_llseek,
+ .llseek = xfs_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = xfs_file_aio_read,