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zvol_create_minors(): check snapdev before traversing snapshots #2479

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zvol_create_minors(): check snapdev before traversing snapshots #2479

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1 change: 0 additions & 1 deletion include/sys/zvol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,6 @@ extern int zvol_check_volblocksize(const char *name, uint64_t volblocksize);
extern int zvol_get_stats(objset_t *os, nvlist_t *nv);
extern boolean_t zvol_is_zvol(const char *);
extern void zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
extern int zvol_create_minor(const char *name);
extern int zvol_create_minors(const char *name);
extern int zvol_remove_minor(const char *name);
extern void zvol_remove_minors(const char *name);
Expand Down
5 changes: 0 additions & 5 deletions module/zfs/zfs_ioctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3305,11 +3305,6 @@ zfs_ioc_snapshot(const char *poolname, nvlist_t *innvl, nvlist_t *outnvl)

error = dsl_dataset_snapshot(snaps, props, outnvl);

#ifdef _KERNEL
if (error == 0)
zvol_create_minors(poolname);
#endif

return (error);
}

Expand Down
117 changes: 76 additions & 41 deletions module/zfs/zvol.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,9 @@
#include <sys/zvol.h>
#include <linux/blkdev_compat.h>

static int
zvol_create_minors_cb(const char *dsname, void *arg);

unsigned int zvol_inhibit_dev = 0;
unsigned int zvol_major = ZVOL_MAJOR;
unsigned int zvol_prefetch_bytes = (128 * 1024);
Expand Down Expand Up @@ -1269,30 +1272,7 @@ zvol_free(zvol_state_t *zv)
}

static int
__zvol_snapdev_hidden(const char *name)
{
uint64_t snapdev;
char *parent;
char *atp;
int error = 0;

parent = kmem_alloc(MAXPATHLEN, KM_SLEEP);
(void) strlcpy(parent, name, MAXPATHLEN);

if ((atp = strrchr(parent, '@')) != NULL) {
*atp = '\0';
error = dsl_prop_get_integer(parent, "snapdev", &snapdev, NULL);
if ((error == 0) && (snapdev == ZFS_SNAPDEV_HIDDEN))
error = SET_ERROR(ENODEV);
}

kmem_free(parent, MAXPATHLEN);

return (SET_ERROR(error));
}

static int
__zvol_create_minor(const char *name, boolean_t ignore_snapdev)
__zvol_create_minor(const char *name)
{
zvol_state_t *zv;
objset_t *os;
Expand All @@ -1310,13 +1290,7 @@ __zvol_create_minor(const char *name, boolean_t ignore_snapdev)
goto out;
}

if (ignore_snapdev == B_FALSE) {
error = __zvol_snapdev_hidden(name);
if (error)
goto out;
}

doi = kmem_alloc(sizeof (dmu_object_info_t), KM_SLEEP);
doi = kmem_alloc(sizeof (dmu_object_info_t), KM_PUSHPAGE);

error = dmu_objset_own(name, DMU_OST_ZVOL, B_TRUE, zvol_tag, &os);
if (error)
Expand Down Expand Up @@ -1403,15 +1377,35 @@ __zvol_create_minor(const char *name, boolean_t ignore_snapdev)
* Create a block device minor node and setup the linkage between it
* and the specified volume. Once this function returns the block
* device is live and ready for use.
* Check the snapdev option before traversing snapshots of the 'name'.
*/
int
zvol_create_minor(const char *name)
static int
zvol_create_minor(const char *name, uint64_t snapdev)
{
int error;

mutex_enter(&zvol_state_lock);
error = __zvol_create_minor(name, B_FALSE);
mutex_exit(&zvol_state_lock);
if (strchr(name, '@') == 0) {
/* create minor for the 'name' explicitly */
mutex_enter(&zvol_state_lock);
error = __zvol_create_minor(name);
mutex_exit(&zvol_state_lock);
if (error == 0 && snapdev == ZFS_SNAPDEV_VISIBLE) {
/*
* traverse snapshots only, do not traverse children,
* and skip the 'name'
*/
error = dmu_objset_find((char *)name,
zvol_create_minors_cb, (void *)name,
DS_FIND_SNAPSHOTS);
}
} else {
if (snapdev == ZFS_SNAPDEV_VISIBLE) {
/* create minor for the snapshot */
mutex_enter(&zvol_state_lock);
error = __zvol_create_minor(name);
mutex_exit(&zvol_state_lock);
}
}

return (SET_ERROR(error));
}
Expand Down Expand Up @@ -1475,25 +1469,66 @@ __zvol_rename_minor(zvol_state_t *zv, const char *newname)
set_disk_ro(zv->zv_disk, readonly);
}

/* Mask errors to continue dmu_objset_find() traversal */
static int
zvol_create_minors_cb(const char *dsname, void *arg)
{
(void) zvol_create_minor(dsname);
const char *name = (const char *)arg;
uint64_t snapdev;
int error;

/* skip the designated dataset */
if (name && strcmp(dsname, name) == 0)
return 0;

error = dsl_prop_get_integer(dsname, "snapdev", &snapdev, NULL);
if (error)
return (0);

(void) zvol_create_minor(dsname, snapdev);

return (0);
}

/*
* Create minors for specified dataset including children and snapshots.
* Pay attention to the 'snapdev' property and traverse the snapshots
* only if the property is set.
*/
int
zvol_create_minors(const char *name)
{
int error = 0;

if (!zvol_inhibit_dev)
error = dmu_objset_find((char *)name, zvol_create_minors_cb,
NULL, DS_FIND_CHILDREN | DS_FIND_SNAPSHOTS);
/*
* dmu_objset_find() does not expect snapshot name (with '@') in its
* first argument. So, check for the '@' in the name.
*/
if (!zvol_inhibit_dev) {
char *atp, *parent;

parent = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
(void) strlcpy(parent, name, MAXPATHLEN);

if ((atp = strrchr(parent, '@')) != NULL) {
uint64_t snapdev;

*atp = '\0';
error = dsl_prop_get_integer(parent, "snapdev",
&snapdev, NULL);

if (error == 0 && snapdev == ZFS_SNAPDEV_VISIBLE) {
mutex_enter(&zvol_state_lock);
error = __zvol_create_minor(name);
mutex_exit(&zvol_state_lock);
}
} else {
error = dmu_objset_find(parent, zvol_create_minors_cb,
NULL, DS_FIND_CHILDREN);
}

kmem_free(parent, MAXPATHLEN);
}

return (SET_ERROR(error));
}
Expand Down Expand Up @@ -1575,7 +1610,7 @@ snapdev_snapshot_changed_cb(const char *dsname, void *arg) {
switch (snapdev) {
case ZFS_SNAPDEV_VISIBLE:
mutex_enter(&zvol_state_lock);
(void) __zvol_create_minor(dsname, B_TRUE);
(void) __zvol_create_minor(dsname);
mutex_exit(&zvol_state_lock);
break;
case ZFS_SNAPDEV_HIDDEN:
Expand Down