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Linux 5.11 compat: lookup_bdev()
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The lookup_bdev() function has been updated to require a dev_t
be passed as the second argument. This is actually pretty nice
since the major number stored in the dev_t was the only part we
were interested in. This allows to us avoid handling the bdev
entirely.  The vdev_lookup_bdev() wrapper was updated to emulate
the behavior of the new lookup_bdev() for all supported kernels.

Reviewed-by: Rafael Kitover <[email protected]>
Reviewed-by: Coleman Kane <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes openzfs#11387
Closes openzfs#11390
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behlendorf authored and RageLtMan committed May 31, 2021
1 parent bb38346 commit 857c3ca
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Showing 3 changed files with 74 additions and 30 deletions.
55 changes: 41 additions & 14 deletions config/kernel-blkdev.m4
Original file line number Diff line number Diff line change
Expand Up @@ -154,42 +154,69 @@ AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_INVALIDATE_BDEV], [
])

dnl #
dnl # 2.6.27, lookup_bdev() was exported.
dnl # 4.4.0-6.21 - lookup_bdev() takes 2 arguments.
dnl # 5.11 API, lookup_bdev() takes dev_t argument.
dnl # 2.6.27 API, lookup_bdev() was first exported.
dnl # 4.4.0-6.21 API, lookup_bdev() on Ubuntu takes mode argument.
dnl #
AC_DEFUN([ZFS_AC_KERNEL_SRC_BLKDEV_LOOKUP_BDEV], [
ZFS_LINUX_TEST_SRC([lookup_bdev_devt], [
#include <linux/blkdev.h>
], [
int error __attribute__ ((unused));
const char path[] = "/example/path";
dev_t dev;
error = lookup_bdev(path, &dev);
])
ZFS_LINUX_TEST_SRC([lookup_bdev_1arg], [
#include <linux/fs.h>
#include <linux/blkdev.h>
], [
lookup_bdev(NULL);
struct block_device *bdev __attribute__ ((unused));
const char path[] = "/example/path";
bdev = lookup_bdev(path);
])
ZFS_LINUX_TEST_SRC([lookup_bdev_2args], [
ZFS_LINUX_TEST_SRC([lookup_bdev_mode], [
#include <linux/fs.h>
], [
lookup_bdev(NULL, FMODE_READ);
struct block_device *bdev __attribute__ ((unused));
const char path[] = "/example/path";
bdev = lookup_bdev(path, FMODE_READ);
])
])

AC_DEFUN([ZFS_AC_KERNEL_BLKDEV_LOOKUP_BDEV], [
AC_MSG_CHECKING([whether lookup_bdev() wants 1 arg])
ZFS_LINUX_TEST_RESULT_SYMBOL([lookup_bdev_1arg],
AC_MSG_CHECKING([whether lookup_bdev() wants dev_t arg])
ZFS_LINUX_TEST_RESULT_SYMBOL([lookup_bdev_devt],
[lookup_bdev], [fs/block_dev.c], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_1ARG_LOOKUP_BDEV, 1,
[lookup_bdev() wants 1 arg])
AC_DEFINE(HAVE_DEVT_LOOKUP_BDEV, 1,
[lookup_bdev() wants dev_t arg])
], [
AC_MSG_RESULT(no)
AC_MSG_CHECKING([whether lookup_bdev() wants 2 args])
ZFS_LINUX_TEST_RESULT_SYMBOL([lookup_bdev_2args],
AC_MSG_CHECKING([whether lookup_bdev() wants 1 arg])
ZFS_LINUX_TEST_RESULT_SYMBOL([lookup_bdev_1arg],
[lookup_bdev], [fs/block_dev.c], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_2ARGS_LOOKUP_BDEV, 1,
[lookup_bdev() wants 2 args])
AC_DEFINE(HAVE_1ARG_LOOKUP_BDEV, 1,
[lookup_bdev() wants 1 arg])
], [
ZFS_LINUX_TEST_ERROR([lookup_bdev()])
AC_MSG_RESULT(no)
AC_MSG_CHECKING([whether lookup_bdev() wants mode arg])
ZFS_LINUX_TEST_RESULT_SYMBOL([lookup_bdev_mode],
[lookup_bdev], [fs/block_dev.c], [
AC_MSG_RESULT(yes)
AC_DEFINE(HAVE_MODE_LOOKUP_BDEV, 1,
[lookup_bdev() wants mode arg])
], [
ZFS_LINUX_TEST_ERROR([lookup_bdev()])
])
])
])
])
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36 changes: 29 additions & 7 deletions include/os/linux/kernel/linux/blkdev_compat.h
Original file line number Diff line number Diff line change
Expand Up @@ -318,16 +318,38 @@ zfs_check_media_change(struct block_device *bdev)
*
* 4.4.0-6.21 API change for Ubuntu
* lookup_bdev() gained a second argument, FMODE_*, to check inode permissions.
*
* 5.11 API change
* Changed to take a dev_t argument which is set on success and return a
* non-zero error code on failure.
*/
#ifdef HAVE_1ARG_LOOKUP_BDEV
#define vdev_lookup_bdev(path) lookup_bdev(path)
#else
#ifdef HAVE_2ARGS_LOOKUP_BDEV
#define vdev_lookup_bdev(path) lookup_bdev(path, 0)
static inline int
vdev_lookup_bdev(const char *path, dev_t *dev)
{
#if defined(HAVE_DEVT_LOOKUP_BDEV)
return (lookup_bdev(path, dev));
#elif defined(HAVE_1ARG_LOOKUP_BDEV)
struct block_device *bdev = lookup_bdev(path);
if (IS_ERR(bdev))
return (PTR_ERR(bdev));

*dev = bdev->bd_dev;
bdput(bdev);

return (0);
#elif defined(HAVE_MODE_LOOKUP_BDEV)
struct block_device *bdev = lookup_bdev(path, FMODE_READ);
if (IS_ERR(bdev))
return (PTR_ERR(bdev));

*dev = bdev->bd_dev;
bdput(bdev);

return (0);
#else
#error "Unsupported kernel"
#endif /* HAVE_2ARGS_LOOKUP_BDEV */
#endif /* HAVE_1ARG_LOOKUP_BDEV */
#endif
}

/*
* Kernels without bio_set_op_attrs use bi_rw for the bio flags.
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13 changes: 4 additions & 9 deletions module/os/linux/zfs/zvol_os.c
Original file line number Diff line number Diff line change
Expand Up @@ -66,19 +66,14 @@ typedef struct zv_request {
* Given a path, return TRUE if path is a ZVOL.
*/
static boolean_t
zvol_is_zvol_impl(const char *device)
zvol_is_zvol_impl(const char *path)
{
struct block_device *bdev;
unsigned int major;
dev_t dev = 0;

bdev = vdev_lookup_bdev(device);
if (IS_ERR(bdev))
if (vdev_lookup_bdev(path, &dev) != 0)
return (B_FALSE);

major = MAJOR(bdev->bd_dev);
bdput(bdev);

if (major == zvol_major)
if (MAJOR(dev) == zvol_major)
return (B_TRUE);

return (B_FALSE);
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