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xfs: introduce SEEK_DATA/SEEK_HOLE support

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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>
This commit is contained in:
Jeff Liu 2012-05-10 21:29:17 +08:00 committed by Ben Myers
parent e700a06c71
commit 3fe3e6b182
1 changed files with 142 additions and 1 deletions
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143
fs/xfs/xfs_file.c
View file

@ -963,8 +963,149 @@ xfs_vm_page_mkwrite(
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,