sunrpc: fix cache_head leak due to queued request

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commit 4ecd55ea07 upstream.

After commit d202cce896, an expired cache_head can be removed from the
cache_detail's hash.

However, the expired cache_head may be waiting for a reply from a
previously submitted request. Such a cache_head has an increased
refcounter and therefore it won't be freed after cache_put(freeme).

Because the cache_head was removed from the hash it cannot be found
during cache_clean() and can be leaked forever, together with stalled
cache_request and other taken resources.

In our case we noticed it because an entry in the export cache was
holding a reference on a filesystem.

Fixes d202cce896 ("sunrpc: never return expired entries in sunrpc_cache_lookup")
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
[bwh: Backported to 3.16:
 - cache_fresh_lock() doesn't take a struct cache_detail pointer
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

...

This commit is contained in:

Vasily Averin 2018-11-28 11:45:57 +03:00 • committed by Ben Hutchings

parent e605566013

commit 06c27396e8

1 changed files with 8 additions and 1 deletions

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net/sunrpc/cache.c

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