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Suspend/resume zvol for recv and rollback

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When doing recv and rollback, dsl_dataset_clone_swap_sync_impl will be
called to swap out the ds_objset and do dmu_objset_evict on the old one.
However, currently zv->zv_objset will not be swapped out accordingly, so
if anyone currently holds a fd on the zvol, we risk hitting a use-after-free.

We fix this by introducing the suspend and resume mechanism of zsb to
zv.  Before recv or rollback, we use zvol_suspend to block all access to
zv_objset and shut it down. After the recv or rollback, we use zvol_resume
to swap in zv_objset with the new ds_objset and unblock the access.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes #4866 
Closes #5609
This commit is contained in:
Chunwei Chen
2017-01-19 13:56:36 -08:00
committed by Brian Behlendorf
parent 76fe529b39
commit 040dab9939
4 changed files with 168 additions and 42 deletions
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include/sys/zvol.h
+5 -2
View File
@@ -35,14 +35,14 @@
#define SPEC_MAXOFFSET_T ((1LL << ((NBBY * sizeof (daddr32_t)) + \
DEV_BSHIFT - 1)) - 1)
extern void *zvol_tag;
extern void zvol_create_minors(spa_t *spa, const char *name, boolean_t async);
extern void zvol_remove_minors(spa_t *spa, const char *name, boolean_t async);
extern void zvol_rename_minors(spa_t *spa, const char *oldname,
const char *newname, boolean_t async);
#ifdef _KERNEL
typedef struct zvol_state zvol_state_t;
extern int zvol_check_volsize(uint64_t volsize, uint64_t blocksize);
extern int zvol_check_volblocksize(const char *name, uint64_t volblocksize);
extern int zvol_get_stats(objset_t *os, nvlist_t *nv);
@@ -51,6 +51,9 @@ extern void zvol_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx);
extern int zvol_set_volsize(const char *, uint64_t);
extern int zvol_set_volblocksize(const char *, uint64_t);
extern int zvol_set_snapdev(const char *, zprop_source_t, uint64_t);
extern zvol_state_t *zvol_suspend(const char *);
extern int zvol_resume(zvol_state_t *);
extern void *zvol_tag(zvol_state_t *);
extern int zvol_init(void);
extern void zvol_fini(void);