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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Makefile.am	Fix out-of-tree build failures	2019-06-24 09:32:47 -07:00
linux.run	Fix /etc/hostid on root pool deadlock	2019-09-10 13:42:30 -07:00
longevity.run	OpenZFS 9166 - zfs storage pool checkpoint	2018-06-26 10:07:42 -07:00
perf-regression.run	OpenZFS 9184 - Add ZFS performance test for fixed blocksize random read/write IO	2018-07-02 13:46:06 -07:00