Matthew Ahrens 02dc43bc46 OpenZFS 8378 - crash due to bp in-memory modification of nopwrite block ... Authored by: Matthew Ahrens <mahrens@delphix.com> Reviewed by: Prakash Surya <prakash.surya@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Approved by: Robert Mustacchi <rm@joyent.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov> The problem is that zfs_get_data() supplies a stale zgd_bp to dmu_sync(), which we then nopwrite against. zfs_get_data() doesn't hold any DMU-related locks, so after it copies db_blkptr to zgd_bp, dbuf_write_ready() could change db_blkptr, and dbuf_write_done() could remove the dirty record. dmu_sync() then sees the stale BP and that the dbuf it not dirty, so it is eligible for nop-writing. The fix is for dmu_sync() to copy db_blkptr to zgd_bp after acquiring the db_mtx. We could still see a stale db_blkptr, but if it is stale then the dirty record will still exist and thus we won't attempt to nopwrite. OpenZFS-issue: https://www.illumos.org/issues/8378 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/3127742 Closes #6293		2017-07-04 15:41:24 -07:00
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.gitignore	Add .gitignore files to exclude build products	2010-01-08 11:35:17 -08:00
Makefile.am	GCC 7.1 fixes	2017-06-28 10:05:16 -07:00
ztest.c	OpenZFS 8378 - crash due to bp in-memory modification of nopwrite block	2017-07-04 15:41:24 -07:00