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Add SEEK_DATA/SEEK_HOLE to lseek()/llseek()

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The approach taken was the rework zfs_holey() as little as
possible and then just wrap the code as needed to ensure
correct locking and error handling.

Tested with xfstests 285 and 286.  All tests pass except for
7-9 of 285 which try to reserve blocks first via fallocate(2)
and fail because fallocate(2) is not yet supported.

Note that the filp->f_lock spinlock did not exist prior to
Linux 2.6.30, but we avoid the need for autotools check by
virtue of the fact that SEEK_DATA/SEEK_HOLE support was not
added until Linux 3.1.

An autoconf check was added for lseek_execute() which is
currently a private function but the expectation is that it
will be exported perhaps as early as Linux 3.11.

Reviewed-by: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1384
This commit is contained in:
Li Dongyang
2013-06-13 13:51:09 -04:00
committed by Brian Behlendorf
parent cf91b2b6b2
commit 802e7b5feb
6 changed files with 97 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/zfs_vnops.c
+27 -10
View File
@@ -240,15 +240,15 @@ zfs_close(struct inode *ip, int flag, cred_t *cr)
}
EXPORT_SYMBOL(zfs_close);
#if 0
#if defined(SEEK_HOLE) && defined(SEEK_DATA)
/*
* Lseek support for finding holes (cmd == _FIO_SEEK_HOLE) and
* data (cmd == _FIO_SEEK_DATA). "off" is an in/out parameter.
* Lseek support for finding holes (cmd == SEEK_HOLE) and
* data (cmd == SEEK_DATA). "off" is an in/out parameter.
*/
static int
zfs_holey(vnode_t *vp, int cmd, offset_t *off)
zfs_holey_common(struct inode *ip, int cmd, loff_t *off)
{
znode_t *zp = VTOZ(vp);
znode_t *zp = ITOZ(ip);
uint64_t noff = (uint64_t)*off; /* new offset */
uint64_t file_sz;
int error;
@@ -256,15 +256,15 @@ zfs_holey(vnode_t *vp, int cmd, offset_t *off)
file_sz = zp->z_size;
if (noff >= file_sz) {
return (SET_ERROR(ENXIO));
return (ENXIO);
}
if (cmd == _FIO_SEEK_HOLE)
if (cmd == SEEK_HOLE)
hole = B_TRUE;
else
hole = B_FALSE;
error = dmu_offset_next(zp->z_zfsvfs->z_os, zp->z_id, hole, &noff);
error = dmu_offset_next(ZTOZSB(zp)->z_os, zp->z_id, hole, &noff);
/* end of file? */
if ((error == ESRCH) || (noff > file_sz)) {
@@ -275,7 +275,7 @@ zfs_holey(vnode_t *vp, int cmd, offset_t *off)
*off = file_sz;
return (0);
}
return (SET_ERROR(ENXIO));
return (ENXIO);
}
if (noff < *off)
@@ -283,7 +283,24 @@ zfs_holey(vnode_t *vp, int cmd, offset_t *off)
*off = noff;
return (error);
}
#endif
int
zfs_holey(struct inode *ip, int cmd, loff_t *off)
{
znode_t *zp = ITOZ(ip);
zfs_sb_t *zsb = ITOZSB(ip);
int error;
ZFS_ENTER(zsb);
ZFS_VERIFY_ZP(zp);
error = zfs_holey_common(ip, cmd, off);
ZFS_EXIT(zsb);
return (error);
}
EXPORT_SYMBOL(zfs_holey);
#endif /* SEEK_HOLE && SEEK_DATA */
#if defined(_KERNEL)
/*
module/zfs/zpl_file.c
+23 -1
View File
@@ -235,6 +235,28 @@ zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
return (wrote);
}
static loff_t
zpl_llseek(struct file *filp, loff_t offset, int whence)
{
#if defined(SEEK_HOLE) && defined(SEEK_DATA)
if (whence == SEEK_DATA || whence == SEEK_HOLE) {
struct inode *ip = filp->f_mapping->host;
loff_t maxbytes = ip->i_sb->s_maxbytes;
loff_t error;
spl_inode_lock(ip);
error = -zfs_holey(ip, whence, &offset);
if (error == 0)
error = lseek_execute(filp, ip, offset, maxbytes);
spl_inode_unlock(ip);
return (error);
}
#endif /* SEEK_HOLE && SEEK_DATA */
return generic_file_llseek(filp, offset, whence);
}
/*
* It's worth taking a moment to describe how mmap is implemented
* for zfs because it differs considerably from other Linux filesystems.
@@ -464,7 +486,7 @@ const struct address_space_operations zpl_address_space_operations = {
const struct file_operations zpl_file_operations = {
.open = zpl_open,
.release = zpl_release,
.llseek = generic_file_llseek,
.llseek = zpl_llseek,
.read = zpl_read,
.write = zpl_write,
.mmap = zpl_mmap,