Brian Behlendorf 25f06d677a Fix /etc/hostid on root pool deadlock ... Accidentally introduced by dc04a8c which now takes the SCL_VDEV lock as a reader in zfs_blkptr_verify(). A deadlock can occur if the /etc/hostid file resides on a dataset in the same pool. This is because reading the /etc/hostid file may occur while the caller is holding the SCL_VDEV lock as a writer. For example, to perform a `zpool attach` as shown in the abbreviated stack below. To resolve the issue we cache the system's hostid when initializing the spa_t, or when modifying the multihost property. The cached value is then relied upon for subsequent accesses. Call Trace: spa_config_enter+0x1e8/0x350 [zfs] zfs_blkptr_verify+0x33c/0x4f0 [zfs] <--- trying read lock zio_read+0x6c/0x140 [zfs] ... vfs_read+0xfc/0x1e0 kernel_read+0x50/0x90 ... spa_get_hostid+0x1c/0x38 [zfs] spa_config_generate+0x1a0/0x610 [zfs] vdev_label_init+0xa0/0xc80 [zfs] vdev_create+0x98/0xe0 [zfs] spa_vdev_attach+0x14c/0xb40 [zfs] <--- grabbed write lock Reviewed-by: loli10K <ezomori.nozomu@gmail.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #9256 Closes #9285		2019-09-10 13:42:30 -07:00
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avl	Fix typos in module/	2019-08-30 14:32:18 -07:00
icp	OpenZFS restructuring - move platform specific headers	2019-09-05 09:34:54 -07:00
lua	Fix typos in module/	2019-08-30 14:32:18 -07:00
nvpair	Fix typos in module/	2019-08-30 14:32:18 -07:00
os	Enable SIMD for encryption	2019-09-10 10:45:46 -07:00
spl	OpenZFS restructuring - move platform specific sources	2019-09-06 11:26:26 -07:00
unicode	Update build system and packaging	2018-05-29 16:00:33 -07:00
zcommon	Make module tunables cross platform	2019-09-05 14:49:49 -07:00
zfs	Fix /etc/hostid on root pool deadlock	2019-09-10 13:42:30 -07:00
.gitignore	Prepare SPL repo to merge with ZFS repo	2018-05-29 14:51:39 -07:00
Makefile.in	OpenZFS restructuring - move platform specific sources	2019-09-06 11:26:26 -07:00