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xfs: Factor xfs_seek_hole_data into helper 

Factor xfs_seek_hole_data into an unlocked helper which takes
an xfs inode rather than a file for internal use.

Also allow specification of "end" - the vfs lseek interface is
defined such that any offset past eof/i_size shall return -ENXIO,
but we will use this for quota code which does not maintain i_size,
and we want to be able to SEEK_DATA past i_size as well.  So the
lseek path can send in i_size, and the quota code can determine
its own ending offset.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Eric Sandeen 2016-02-08 11:25:16 +11:00 committed by Dave Chinner
parent 4d4d9523b4
commit 8aa7d37ebf
2 changed files with 59 additions and 25 deletions
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82
fs/xfs/xfs_file.c
View File

@ -1337,31 +1337,31 @@ out:
return found;
}
STATIC loff_t
xfs_seek_hole_data(
struct file *file,
/*
* caller must lock inode with xfs_ilock_data_map_shared,
* can we craft an appropriate ASSERT?
*
* end is because the VFS-level lseek interface is defined such that any
* offset past i_size shall return -ENXIO, but we use this for quota code
* which does not maintain i_size, and we want to SEEK_DATA past i_size.
*/
loff_t
__xfs_seek_hole_data(
struct inode *inode,
loff_t start,
loff_t end,
int whence)
{
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);
xfs_fsize_t isize;
xfs_fileoff_t fsbno;
xfs_filblks_t end;
uint lock;
xfs_filblks_t lastbno;
int error;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
lock = xfs_ilock_data_map_shared(ip);
isize = i_size_read(inode);
if (start >= isize) {
if (start >= end) {
error = -ENXIO;
goto out_unlock;
goto out_error;
}
/*
@ -1369,22 +1369,22 @@ xfs_seek_hole_data(
* by fsbno to the end block of the file.
*/
fsbno = XFS_B_TO_FSBT(mp, start);
end = XFS_B_TO_FSB(mp, isize);
lastbno = XFS_B_TO_FSB(mp, end);
for (;;) {
struct xfs_bmbt_irec map[2];
int nmap = 2;
unsigned int i;
error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
error = xfs_bmapi_read(ip, fsbno, lastbno - fsbno, map, &nmap,
XFS_BMAPI_ENTIRE);
if (error)
goto out_unlock;
goto out_error;
/* No extents at given offset, must be beyond EOF */
if (nmap == 0) {
error = -ENXIO;
goto out_unlock;
goto out_error;
}
for (i = 0; i < nmap; i++) {
@ -1426,7 +1426,7 @@ xfs_seek_hole_data(
* hole at the end of any file).
*/
if (whence == SEEK_HOLE) {
offset = isize;
offset = end;
break;
}
/*
@ -1434,7 +1434,7 @@ xfs_seek_hole_data(
*/
ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
goto out_error;
}
ASSERT(i > 1);
@ -1445,14 +1445,14 @@ xfs_seek_hole_data(
*/
fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
start = XFS_FSB_TO_B(mp, fsbno);
if (start >= isize) {
if (start >= end) {
if (whence == SEEK_HOLE) {
offset = isize;
offset = end;
break;
}
ASSERT(whence == SEEK_DATA);
error = -ENXIO;
goto out_unlock;
goto out_error;
}
}
@ -1464,7 +1464,39 @@ out:
* situation in particular.
*/
if (whence == SEEK_HOLE)
offset = min_t(loff_t, offset, isize);
offset = min_t(loff_t, offset, end);
return offset;
out_error:
return error;
}
STATIC loff_t
xfs_seek_hole_data(
struct file *file,
loff_t start,
int whence)
{
struct inode *inode = file->f_mapping->host;
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
uint lock;
loff_t offset, end;
int error = 0;
if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
lock = xfs_ilock_data_map_shared(ip);
end = i_size_read(inode);
offset = __xfs_seek_hole_data(inode, start, end, whence);
if (offset < 0) {
error = offset;
goto out_unlock;
}
offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
out_unlock:

2
fs/xfs/xfs_inode.h
View File

@ -437,6 +437,8 @@ int xfs_update_prealloc_flags(struct xfs_inode *ip,
int xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset,
xfs_fsize_t isize, bool *did_zeroing);
int xfs_iozero(struct xfs_inode *ip, loff_t pos, size_t count);
loff_t __xfs_seek_hole_data(struct inode *inode, loff_t start,
loff_t eof, int whence);
/* from xfs_iops.c */