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Fix self-healing IO prior to dsl_pool_init() completion

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Async writes triggered by a self-healing IO may be issued before the
pool finishes the process of initialization.  This results in a NULL
dereference of `spa->spa_dsl_pool` in vdev_queue_max_async_writes().

George Wilson recommended addressing this issue by initializing the
passed `dsl_pool_t **` prior to dmu_objset_open_impl().  Since the
caller is passing the `spa->spa_dsl_pool` this has the effect of
ensuring it's initialized.

However, since this depends on the caller knowing they must pass
the `spa->spa_dsl_pool` an additional NULL check was added to
vdev_queue_max_async_writes().  This guards against any future
restructuring of the code which might result in dsl_pool_init()
being called differently.

Signed-off-by: GeLiXin <47034221@qq.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4652
This commit is contained in:
GeLiXin
2016-05-21 11:34:06 +08:00
committed by Brian Behlendorf
parent 92547bc45c
commit b7faa7aabd
2 changed files with 23 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/dsl_pool.c
Regular → Executable
+11 -3
View File
@@ -182,12 +182,20 @@ dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
int err;
dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
/*
* Initialize the caller's dsl_pool_t structure before we actually open
* the meta objset. This is done because a self-healing write zio may
* be issued as part of dmu_objset_open_impl() and the spa needs its
* dsl_pool_t initialized in order to handle the write.
*/
*dpp = dp;
err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
&dp->dp_meta_objset);
if (err != 0)
if (err != 0) {
dsl_pool_close(dp);
else
*dpp = dp;
*dpp = NULL;
}
return (err);
}