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Linux 4.1 compat: loop device on ZFS

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Starting from Linux 4.1 allows iov_iter with bio_vec to be passed into
iter_read/iter_write. Notably, the loop device will pass bio_vec to backend
filesystem. However, current ZFS code assumes iovec without any check, so it
will always crash when using loop device.

With the restructured uio_t, we can safely pass bio_vec in uio_t with UIO_BVEC
set. The uio* functions are modified to handle bio_vec case separately.

The const uio_iov causes some warning in xuio related stuff, so explicit
convert them to non const.

Signed-off-by: Chunwei Chen <tuxoko@gmail.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3511
Closes #3640
This commit is contained in:
Chunwei Chen 2015-07-30 22:24:36 +08:00 committed by Brian Behlendorf
parent 17888ae30d
commit 5475aada94
5 changed files with 162 additions and 137 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

197
module/zcommon/zfs_uio.c
View File

@ -35,6 +35,9 @@
* software developed by the University of California, Berkeley, and its
* contributors.
*/
/*
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
/*
* The uio support from OpenSolaris has been added as a short term
@ -46,6 +49,7 @@
#include <sys/types.h>
#include <sys/uio_impl.h>
#include <linux/kmap_compat.h>
/*
* Move "n" bytes at byte address "p"; "rw" indicates the direction
@ -53,20 +57,17 @@
* update to reflect the data which was moved. Returns 0 on success or
* a non-zero errno on failure.
*/
int
uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
static int
uiomove_iov(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
struct iovec *iov;
const struct iovec *iov = uio->uio_iov;
size_t skip = uio->uio_skip;
ulong_t cnt;
ASSERT3U(skip, <, iov->iov_len);
while (n && uio->uio_resid) {
iov = uio->uio_iov;
cnt = MIN(iov->iov_len, n);
if (cnt == 0l) {
uio->uio_iov++;
uio->uio_iovcnt--;
continue;
}
cnt = MIN(iov->iov_len - skip, n);
switch (uio->uio_segflg) {
case UIO_USERSPACE:
case UIO_USERISPACE:
@ -75,22 +76,29 @@ uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
* iov->iov_base = user data pointer
*/
if (rw == UIO_READ) {
if (copy_to_user(iov->iov_base, p, cnt))
if (copy_to_user(iov->iov_base+skip, p, cnt))
return (EFAULT);
} else {
if (copy_from_user(p, iov->iov_base, cnt))
if (copy_from_user(p, iov->iov_base+skip, cnt))
return (EFAULT);
}
break;
case UIO_SYSSPACE:
if (rw == UIO_READ)
bcopy(p, iov->iov_base, cnt);
bcopy(p, iov->iov_base + skip, cnt);
else
bcopy(iov->iov_base, p, cnt);
bcopy(iov->iov_base + skip, p, cnt);
break;
default:
ASSERT(0);
}
iov->iov_base += cnt;
iov->iov_len -= cnt;
skip += cnt;
if (skip == iov->iov_len) {
skip = 0;
uio->uio_iov = (++iov);
uio->uio_iovcnt--;
}
uio->uio_skip = skip;
uio->uio_resid -= cnt;
uio->uio_loffset += cnt;
p = (caddr_t)p + cnt;
@ -98,6 +106,50 @@ uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
}
return (0);
}
static int
uiomove_bvec(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
const struct bio_vec *bv = uio->uio_bvec;
size_t skip = uio->uio_skip;
ulong_t cnt;
ASSERT3U(skip, <, bv->bv_len);
while (n && uio->uio_resid) {
void *paddr;
cnt = MIN(bv->bv_len - skip, n);
paddr = zfs_kmap_atomic(bv->bv_page, KM_USER1);
if (rw == UIO_READ)
bcopy(p, paddr + bv->bv_offset + skip, cnt);
else
bcopy(paddr + bv->bv_offset + skip, p, cnt);
zfs_kunmap_atomic(paddr, KM_USER1);
skip += cnt;
if (skip == bv->bv_len) {
skip = 0;
uio->uio_bvec = (++bv);
uio->uio_iovcnt--;
}
uio->uio_skip = skip;
uio->uio_resid -= cnt;
uio->uio_loffset += cnt;
p = (caddr_t)p + cnt;
n -= cnt;
}
return (0);
}
int
uiomove(void *p, size_t n, enum uio_rw rw, struct uio *uio)
{
if (uio->uio_segflg != UIO_BVEC)
return (uiomove_iov(p, n, rw, uio));
else
return (uiomove_bvec(p, n, rw, uio));
}
EXPORT_SYMBOL(uiomove);
#define fuword8(uptr, vptr) get_user((*vptr), (uptr))
@ -111,39 +163,39 @@ EXPORT_SYMBOL(uiomove);
void
uio_prefaultpages(ssize_t n, struct uio *uio)
{
struct iovec *iov;
const struct iovec *iov;
ulong_t cnt, incr;
caddr_t p;
uint8_t tmp;
int iovcnt;
size_t skip = uio->uio_skip;
/* no need to fault in kernel pages */
switch (uio->uio_segflg) {
case UIO_SYSSPACE:
case UIO_BVEC:
return;
case UIO_USERSPACE:
case UIO_USERISPACE:
break;
default:
ASSERT(0);
}
iov = uio->uio_iov;
iovcnt = uio->uio_iovcnt;
ASSERT3U(skip, <, iov->iov_len);
while ((n > 0) && (iovcnt > 0)) {
cnt = MIN(iov->iov_len, n);
if (cnt == 0) {
/* empty iov entry */
iov++;
iovcnt--;
continue;
}
cnt = MIN(iov->iov_len - skip, n);
n -= cnt;
/*
* touch each page in this segment.
*/
p = iov->iov_base;
p = iov->iov_base + skip;
while (cnt) {
switch (uio->uio_segflg) {
case UIO_USERSPACE:
case UIO_USERISPACE:
if (fuword8((uint8_t *) p, &tmp))
return;
break;
case UIO_SYSSPACE:
bcopy(p, &tmp, 1);
break;
}
incr = MIN(cnt, PAGESIZE);
p += incr;
cnt -= incr;
@ -152,18 +204,11 @@ uio_prefaultpages(ssize_t n, struct uio *uio)
* touch the last byte in case it straddles a page.
*/
p--;
switch (uio->uio_segflg) {
case UIO_USERSPACE:
case UIO_USERISPACE:
if (fuword8((uint8_t *) p, &tmp))
return;
break;
case UIO_SYSSPACE:
bcopy(p, &tmp, 1);
break;
}
iov++;
iovcnt--;
skip = 0;
}
}
EXPORT_SYMBOL(uio_prefaultpages);
@ -175,49 +220,13 @@ EXPORT_SYMBOL(uio_prefaultpages);
int
uiocopy(void *p, size_t n, enum uio_rw rw, struct uio *uio, size_t *cbytes)
{
struct iovec *iov;
ulong_t cnt;
int iovcnt;
struct uio uio_copy;
int ret;
iovcnt = uio->uio_iovcnt;
*cbytes = 0;
for (iov = uio->uio_iov; n && iovcnt; iov++, iovcnt--) {
cnt = MIN(iov->iov_len, n);
if (cnt == 0)
continue;
switch (uio->uio_segflg) {
case UIO_USERSPACE:
case UIO_USERISPACE:
/*
* p = kernel data pointer
* iov->iov_base = user data pointer
*/
if (rw == UIO_READ) {
/* UIO_READ = copy data from kernel to user */
if (copy_to_user(iov->iov_base, p, cnt))
return (EFAULT);
} else {
/* UIO_WRITE = copy data from user to kernel */
if (copy_from_user(p, iov->iov_base, cnt))
return (EFAULT);
}
break;
case UIO_SYSSPACE:
if (rw == UIO_READ)
bcopy(p, iov->iov_base, cnt);
else
bcopy(iov->iov_base, p, cnt);
break;
}
p = (caddr_t)p + cnt;
n -= cnt;
*cbytes += cnt;
}
return (0);
bcopy(uio, &uio_copy, sizeof (struct uio));
ret = uiomove(p, n, rw, &uio_copy);
*cbytes = uio->uio_resid - uio_copy.uio_resid;
return (ret);
}
EXPORT_SYMBOL(uiocopy);
@ -229,21 +238,23 @@ uioskip(uio_t *uiop, size_t n)
{
if (n > uiop->uio_resid)
return;
while (n != 0) {
iovec_t *iovp = uiop->uio_iov;
size_t niovb = MIN(iovp->iov_len, n);
if (niovb == 0) {
uiop->uio_skip += n;
if (uiop->uio_segflg != UIO_BVEC) {
while (uiop->uio_skip >= uiop->uio_iov->iov_len) {
uiop->uio_skip -= uiop->uio_iov->iov_len;
uiop->uio_iov++;
uiop->uio_iovcnt--;
continue;
}
iovp->iov_base += niovb;
uiop->uio_loffset += niovb;
iovp->iov_len -= niovb;
uiop->uio_resid -= niovb;
n -= niovb;
} else {
while (uiop->uio_skip >= uiop->uio_bvec->bv_len) {
uiop->uio_skip -= uiop->uio_bvec->bv_len;
uiop->uio_bvec++;
uiop->uio_iovcnt--;
}
}
uiop->uio_loffset += n;
uiop->uio_resid -= n;
}
EXPORT_SYMBOL(uioskip);
#endif /* _KERNEL */

5
module/zfs/dmu.c
View File

@ -23,6 +23,7 @@
* Copyright (c) 2011, 2014 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2014, Nexenta Systems, Inc. All rights reserved.
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
#include <sys/dmu.h>
@ -933,7 +934,7 @@ dmu_xuio_init(xuio_t *xuio, int nblk)
priv = kmem_zalloc(sizeof (dmu_xuio_t), KM_SLEEP);
priv->cnt = nblk;
priv->bufs = kmem_zalloc(nblk * sizeof (arc_buf_t *), KM_SLEEP);
priv->iovp = uio->uio_iov;
priv->iovp = (iovec_t *)uio->uio_iov;
XUIO_XUZC_PRIV(xuio) = priv;
if (XUIO_XUZC_RW(xuio) == UIO_READ)
@ -974,7 +975,7 @@ dmu_xuio_add(xuio_t *xuio, arc_buf_t *abuf, offset_t off, size_t n)
ASSERT(i < priv->cnt);
ASSERT(off + n <= arc_buf_size(abuf));
iov = uio->uio_iov + i;
iov = (iovec_t *)uio->uio_iov + i;
iov->iov_base = (char *)abuf->b_data + off;
iov->iov_len = n;
priv->bufs[i] = abuf;

6
module/zfs/zfs_vnops.c
View File

@ -21,6 +21,7 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
/* Portions Copyright 2007 Jeremy Teo */
@ -591,10 +592,10 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
int max_blksz = zsb->z_max_blksz;
int error = 0;
arc_buf_t *abuf;
iovec_t *aiov = NULL;
const iovec_t *aiov = NULL;
xuio_t *xuio = NULL;
int i_iov = 0;
iovec_t *iovp = uio->uio_iov;
const iovec_t *iovp = uio->uio_iov;
int write_eof;
int count = 0;
sa_bulk_attr_t bulk[4];
@ -714,6 +715,7 @@ zfs_write(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
if (xuio && abuf == NULL) {
ASSERT(i_iov < iovcnt);
ASSERT3U(uio->uio_segflg, !=, UIO_BVEC);
aiov = &iovp[i_iov];
abuf = dmu_xuio_arcbuf(xuio, i_iov);
dmu_xuio_clear(xuio, i_iov);

81
module/zfs/zpl_file.c
View File

@ -20,6 +20,7 @@
*/
/*
* Copyright (c) 2011, Lawrence Livermore National Security, LLC.
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
@ -202,17 +203,18 @@ zpl_aio_fsync(struct kiocb *kiocb, int datasync)
#error "Unsupported fops->fsync() implementation"
#endif
static inline ssize_t
static ssize_t
zpl_read_common_iovec(struct inode *ip, const struct iovec *iovp, size_t count,
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment,
int flags, cred_t *cr)
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment, int flags,
cred_t *cr, size_t skip)
{
ssize_t read;
uio_t uio;
int error;
fstrans_cookie_t cookie;
uio.uio_iov = (struct iovec *)iovp;
uio.uio_iov = iovp;
uio.uio_skip = skip;
uio.uio_resid = count;
uio.uio_iovcnt = nr_segs;
uio.uio_loffset = *ppos;
@ -242,7 +244,7 @@ zpl_read_common(struct inode *ip, const char *buf, size_t len, loff_t *ppos,
iov.iov_len = len;
return (zpl_read_common_iovec(ip, &iov, len, 1, ppos, segment,
flags, cr));
flags, cr, 0));
}
static ssize_t
@ -261,24 +263,17 @@ zpl_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
static ssize_t
zpl_iter_read_common(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, size_t count)
unsigned long nr_segs, size_t count, uio_seg_t seg, size_t skip)
{
cred_t *cr = CRED();
struct file *filp = kiocb->ki_filp;
ssize_t read;
size_t alloc_size = sizeof (struct iovec) * nr_segs;
struct iovec *iov_tmp = kmem_alloc(alloc_size, KM_SLEEP);
bcopy(iovp, iov_tmp, alloc_size);
ASSERT(iovp);
crhold(cr);
read = zpl_read_common_iovec(filp->f_mapping->host, iov_tmp, count,
nr_segs, &kiocb->ki_pos, UIO_USERSPACE, filp->f_flags, cr);
read = zpl_read_common_iovec(filp->f_mapping->host, iovp, count,
nr_segs, &kiocb->ki_pos, seg, filp->f_flags, cr, skip);
crfree(cr);
kmem_free(iov_tmp, alloc_size);
return (read);
}
@ -286,22 +281,32 @@ zpl_iter_read_common(struct kiocb *kiocb, const struct iovec *iovp,
static ssize_t
zpl_iter_read(struct kiocb *kiocb, struct iov_iter *to)
{
return (zpl_iter_read_common(kiocb, to->iov, to->nr_segs,
iov_iter_count(to)));
ssize_t ret;
uio_seg_t seg = UIO_USERSPACE;
if (to->type & ITER_KVEC)
seg = UIO_SYSSPACE;
if (to->type & ITER_BVEC)
seg = UIO_BVEC;
ret = zpl_iter_read_common(kiocb, to->iov, to->nr_segs,
iov_iter_count(to), seg, to->iov_offset);
if (ret > 0)
iov_iter_advance(to, ret);
return (ret);
}
#else
static ssize_t
zpl_aio_read(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, loff_t pos)
{
return (zpl_iter_read_common(kiocb, iovp, nr_segs, kiocb->ki_nbytes));
return (zpl_iter_read_common(kiocb, iovp, nr_segs, kiocb->ki_nbytes,
UIO_USERSPACE, 0));
}
#endif /* HAVE_VFS_RW_ITERATE */
static inline ssize_t
static ssize_t
zpl_write_common_iovec(struct inode *ip, const struct iovec *iovp, size_t count,
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment,
int flags, cred_t *cr)
unsigned long nr_segs, loff_t *ppos, uio_seg_t segment, int flags,
cred_t *cr, size_t skip)
{
ssize_t wrote;
uio_t uio;
@ -311,7 +316,8 @@ zpl_write_common_iovec(struct inode *ip, const struct iovec *iovp, size_t count,
if (flags & O_APPEND)
*ppos = i_size_read(ip);
uio.uio_iov = (struct iovec *)iovp;
uio.uio_iov = iovp;
uio.uio_skip = skip;
uio.uio_resid = count;
uio.uio_iovcnt = nr_segs;
uio.uio_loffset = *ppos;
@ -340,7 +346,7 @@ zpl_write_common(struct inode *ip, const char *buf, size_t len, loff_t *ppos,
iov.iov_len = len;
return (zpl_write_common_iovec(ip, &iov, len, 1, ppos, segment,
flags, cr));
flags, cr, 0));
}
static ssize_t
@ -359,24 +365,17 @@ zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
static ssize_t
zpl_iter_write_common(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, size_t count)
unsigned long nr_segs, size_t count, uio_seg_t seg, size_t skip)
{
cred_t *cr = CRED();
struct file *filp = kiocb->ki_filp;
ssize_t wrote;
size_t alloc_size = sizeof (struct iovec) * nr_segs;
struct iovec *iov_tmp = kmem_alloc(alloc_size, KM_SLEEP);
bcopy(iovp, iov_tmp, alloc_size);
ASSERT(iovp);
crhold(cr);
wrote = zpl_write_common_iovec(filp->f_mapping->host, iov_tmp, count,
nr_segs, &kiocb->ki_pos, UIO_USERSPACE, filp->f_flags, cr);
wrote = zpl_write_common_iovec(filp->f_mapping->host, iovp, count,
nr_segs, &kiocb->ki_pos, seg, filp->f_flags, cr, skip);
crfree(cr);
kmem_free(iov_tmp, alloc_size);
return (wrote);
}
@ -384,15 +383,25 @@ zpl_iter_write_common(struct kiocb *kiocb, const struct iovec *iovp,
static ssize_t
zpl_iter_write(struct kiocb *kiocb, struct iov_iter *from)
{
return (zpl_iter_write_common(kiocb, from->iov, from->nr_segs,
iov_iter_count(from)));
ssize_t ret;
uio_seg_t seg = UIO_USERSPACE;
if (from->type & ITER_KVEC)
seg = UIO_SYSSPACE;
if (from->type & ITER_BVEC)
seg = UIO_BVEC;
ret = zpl_iter_write_common(kiocb, from->iov, from->nr_segs,
iov_iter_count(from), seg, from->iov_offset);
if (ret > 0)
iov_iter_advance(from, ret);
return (ret);
}
#else
static ssize_t
zpl_aio_write(struct kiocb *kiocb, const struct iovec *iovp,
unsigned long nr_segs, loff_t pos)
{
return (zpl_iter_write_common(kiocb, iovp, nr_segs, kiocb->ki_nbytes));
return (zpl_iter_write_common(kiocb, iovp, nr_segs, kiocb->ki_nbytes,
UIO_USERSPACE, 0));
}
#endif /* HAVE_VFS_RW_ITERATE */

2
module/zfs/zpl_inode.c
View File

@ -20,6 +20,7 @@
*/
/*
* Copyright (c) 2011, Lawrence Livermore National Security, LLC.
* Copyright (c) 2015 by Chunwei Chen. All rights reserved.
*/
@ -371,6 +372,7 @@ zpl_follow_link(struct dentry *dentry, void **symlink_cookie)
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_skip = 0;
uio.uio_resid = (MAXPATHLEN - 1);
uio.uio_segflg = UIO_SYSSPACE;