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Add zio_ddt_free()+ddt_phys_decref() error handling 

The assumption in zio_ddt_free() is that ddt_phys_select() must
always find a match.  However, if that fails due to a damaged
DDT or some other reason the code will NULL dereference in
ddt_phys_decref().

While this should never happen it has been observed on various
platforms.  The result is that unless your willing to patch the
ZFS code the pool is inaccessible.  Therefore, we're choosing
to more gracefully handle this case rather than leave it fatal.

http://mail.opensolaris.org/pipermail/zfs-discuss/2012-February/050972.html

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1308
This commit is contained in:
Brian Behlendorf 2013-03-19 12:05:08 -07:00
parent 30b92c1de6
commit 5dc6af0eec
2 changed files with 9 additions and 4 deletions
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2
module/zfs/ddt.c
View File

@ -323,8 +323,10 @@ ddt_phys_addref(ddt_phys_t *ddp)
void void
ddt_phys_decref(ddt_phys_t *ddp) ddt_phys_decref(ddt_phys_t *ddp)
{ {
if (ddp) {
ASSERT((int64_t)ddp->ddp_refcnt > 0); ASSERT((int64_t)ddp->ddp_refcnt > 0);
ddp->ddp_refcnt--; ddp->ddp_refcnt--;
}
} }
void void

3
module/zfs/zio.c
View File

@ -2249,8 +2249,11 @@ zio_ddt_free(zio_t *zio)
ddt_enter(ddt); ddt_enter(ddt);
freedde = dde = ddt_lookup(ddt, bp, B_TRUE); freedde = dde = ddt_lookup(ddt, bp, B_TRUE);
if (dde) {
ddp = ddt_phys_select(dde, bp); ddp = ddt_phys_select(dde, bp);
if (ddp)
ddt_phys_decref(ddp); ddt_phys_decref(ddp);
}
ddt_exit(ddt); ddt_exit(ddt);
return (ZIO_PIPELINE_CONTINUE); return (ZIO_PIPELINE_CONTINUE);