vfs: export lseek_execute() to modules

For those file systems(btrfs/ext4/ocfs2/tmpfs) that support
SEEK_DATA/SEEK_HOLE functions, we end up handling the similar
matter in lseek_execute() to update the current file offset
to the desired offset if it is valid, ceph also does the
simliar things at ceph_llseek().

To reduce the duplications, this patch make lseek_execute()
public accessible so that we can call it directly from the
underlying file systems.

Thanks Dave Chinner for this suggestion.

[AV: call it vfs_setpos(), don't bring the removed 'inode' argument back]

v2->v1:
- Add kernel-doc comments for lseek_execute()
- Call lseek_execute() in ceph->llseek()

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: Josef Bacik <jbacik@fusionio.com>
Cc: Ben Myers <bpm@sgi.com>
Cc: Ted Tso <tytso@mit.edu>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Sage Weil <sage@inktank.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 22 deletions

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index b1b4d51b5d86..469361dbe619 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -494,17 +494,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 	if (dataoff > isize)
 		return -ENXIO;
 
-	if (dataoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
-		return -EINVAL;
-	if (dataoff > maxsize)
-		return -EINVAL;
-
-	if (dataoff != file->f_pos) {
-		file->f_pos = dataoff;
-		file->f_version = 0;
-	}
-
-	return dataoff;
+	return vfs_setpos(file, dataoff, maxsize);
 }
 
 /*
@@ -580,17 +570,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 	if (holeoff > isize)
 		holeoff = isize;
 
-	if (holeoff < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET))
-		return -EINVAL;
-	if (holeoff > maxsize)
-		return -EINVAL;
-
-	if (holeoff != file->f_pos) {
-		file->f_pos = holeoff;
-		file->f_version = 0;
-	}
-
-	return holeoff;
+	return vfs_setpos(file, holeoff, maxsize);
 }
 
 /*