zfs/module
Brian Behlendorf 8a02d01e85
Fix zvol_open() lock inversion
When restructuring the zvol_open() logic for the Linux 5.13 kernel
a lock inversion was accidentally introduced.  In the updated code
the spa_namespace_lock is now taken before the zv_suspend_lock
allowing the following scenario to occur:

    down_read <=== waiting for zv_suspend_lock
    zvol_open <=== holds spa_namespace_lock
    __blkdev_get
    blkdev_get_by_dev
    blkdev_open
    ...

     mutex_lock <== waiting for spa_namespace_lock
     spa_open_common
     spa_open
     dsl_pool_hold
     dmu_objset_hold_flags
     dmu_objset_hold
     dsl_prop_get
     dsl_prop_get_integer
     zvol_create_minor
     dmu_recv_end
     zfs_ioc_recv_impl <=== holds zv_suspend_lock via zvol_suspend()
     zfs_ioc_recv
     ...

This commit resolves the issue by moving the acquisition of the
spa_namespace_lock back to after the zv_suspend_lock which restores
the original ordering.

Additionally, as part of this change the error exit paths were
simplified where possible.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Rich Ercolani <rincebrain@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #12863
2021-12-17 09:52:13 -08:00
..
avl Remove avl_size field from struct avl_tree 2021-07-01 09:32:31 -06:00
icp Use fallthrough macro 2021-09-14 10:17:54 -06:00
lua Use fallthrough macro 2021-09-14 10:17:54 -06:00
nvpair Add `const` to nvlist functions to properly expose their real behavior 2021-12-06 18:19:13 -07:00
os Fix zvol_open() lock inversion 2021-12-17 09:52:13 -08:00
spl Cleanup linux module kbuild files 2020-06-10 09:24:15 -07:00
unicode Update `checkstyle` workflow env to ubuntu-20.04 2021-11-02 14:02:57 -06:00
zcommon zcommon: pre-iterate over sysfs instead of statting every feature 2021-12-16 16:43:10 -08:00
zfs zfs list: Allow more fields in ZFS_ITER_SIMPLE mode 2021-12-16 11:56:22 -08:00
zstd Linux 5.16: Resolve ZSTD_isError symbol collision in Linux kernel 2021-12-07 12:28:22 -08:00
.gitignore Cleanup linux module kbuild files 2020-06-10 09:24:15 -07:00
Kbuild.in Add zstd support to zfs 2020-08-20 10:30:06 -07:00
Makefile.bsd Code cleanups 2021-11-30 10:32:38 -08:00
Makefile.in Update `checkstyle` workflow env to ubuntu-20.04 2021-11-02 14:02:57 -06:00