Author: snb
Date: Wed Jun 17 18:55:29 2009
New Revision: 194387
URL: http://svn.freebsd.org/changeset/base/194387
Log:
Keep dirhash tailq locked throughout the entirety of ufsdirhash_destroy() to
fix
a potential race pointed out by pjd. Also use TAILQ_FOREACH_SAFE to iterate
over
dirhashes in ufsdirhash_lowmem(), so that we can continue iterating even
after a
dirhash is destroyed.
Suggested by: pjd
Tested by: pho
Approved by: dwmalone (mentor)
Modified:
head/sys/ufs/ufs/ufs_dirhash.c
Modified: head/sys/ufs/ufs/ufs_dirhash.c
==============================================================================
--- head/sys/ufs/ufs/ufs_dirhash.c Wed Jun 17 18:52:42 2009
(r194386)
+++ head/sys/ufs/ufs/ufs_dirhash.c Wed Jun 17 18:55:29 2009
(r194387)
@@ -1191,16 +1191,14 @@ ufsdirhash_destroy(struct dirhash *dh)
mem = dh->dh_memreq;
dh->dh_memreq = 0;
- /* Unlock everything, free the detached memory. */
+ /* Unlock dirhash and free the detached memory. */
ufsdirhash_release(dh);
- DIRHASHLIST_UNLOCK();
for (i = 0; i < narrays; i++)
DIRHASH_BLKFREE(hash[i]);
free(hash, M_DIRHASH);
free(blkfree, M_DIRHASH);
/* Account for the returned memory. */
- DIRHASHLIST_LOCK();
ufs_dirhashmem -= mem;
return (mem);
@@ -1247,7 +1245,7 @@ ufsdirhash_recycle(int wanted)
static void
ufsdirhash_lowmem()
{
- struct dirhash *dh;
+ struct dirhash *dh, *dh_temp;
int memfreed = 0;
/* XXX: this 10% may need to be adjusted */
int memwanted = ufs_dirhashmem / 10;
@@ -1259,8 +1257,7 @@ ufsdirhash_lowmem()
* Delete dirhashes not used for more than ufs_dirhashreclaimage
* seconds. If we can't get a lock on the dirhash, it will be skipped.
*/
- for (dh = TAILQ_FIRST(&ufsdirhash_list); dh != NULL; dh =
- TAILQ_NEXT(dh, dh_list)) {
+ TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) {
if (!sx_try_xlock(&dh->dh_lock))
continue;
if (time_second - dh->dh_lastused > ufs_dirhashreclaimage)
@@ -1275,11 +1272,14 @@ ufsdirhash_lowmem()
* of the dirhash list. The ones closest to the head should be the
* oldest.
*/
- for (dh = TAILQ_FIRST(&ufsdirhash_list); memfreed < memwanted &&
- dh !=NULL; dh = TAILQ_NEXT(dh, dh_list)) {
- if (!sx_try_xlock(&dh->dh_lock))
- continue;
- memfreed += ufsdirhash_destroy(dh);
+ if (memfreed < memwanted) {
+ TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) {
+ if (!sx_try_xlock(&dh->dh_lock))
+ continue;
+ memfreed += ufsdirhash_destroy(dh);
+ if (memfreed >= memwanted)
+ break;
+ }
}
DIRHASHLIST_UNLOCK();
}
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