Commit fd3b3e0e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fscache-fixes-20181130' of... 

Merge tag 'fscache-fixes-20181130' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache and cachefiles fixes from David Howells:
 "Misc fixes:

   - Fix an assertion failure at fs/cachefiles/xattr.c:138 caused by a
     race between a cache object lookup failing and someone attempting
     to reenable that object, thereby triggering an update of the
     object's attributes.

   - Fix an assertion failure at fs/fscache/operation.c:449 caused by a
     split atomic subtract and atomic read that allows a race to happen.

   - Fix a leak of backing pages when simultaneously reading the same
     page from the same object from two or more threads.

   - Fix a hang due to a race between a cache object being discarded and
     the corresponding cookie being reenabled.

  There are also some minor cleanups:

   - Cast an enum value to a different enum type to prevent clang from
     generating a warning. This shouldn't cause any sort of change in
     the emitted code.

   - Use ktime_get_real_seconds() instead of get_seconds(). This is just
     used to uniquify a filename for an object to be placed in the
     graveyard. Objects placed there are deleted by cachfilesd in
     userspace immediately thereafter.

   - Remove an initialised, but otherwise unused variable. This should
     have been entirely optimised away anyway"

* tag 'fscache-fixes-20181130' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  fscache, cachefiles: remove redundant variable 'cache'
  cachefiles: avoid deprecated get_seconds()
  cachefiles: Explicitly cast enumerated type in put_object
  fscache: fix race between enablement and dropping of object
  cachefiles: Fix page leak in cachefiles_read_backing_file while vmscan is active
  fscache: Fix race in fscache_op_complete() due to split atomic_sub & read
  cachefiles: Fix an assertion failure when trying to update a failed object
parents 38c7b224 31ffa563

fs/cachefiles/namei.c

+5 −3
Original line number Diff line number Diff line
@@ -244,11 +244,13 @@ wait_for_old_object: 


	ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));



	cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_retry);

	cache->cache.ops->put_object(&xobject->fscache,

		(enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);

	goto try_again;



requeue:

	cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_timeo);

	cache->cache.ops->put_object(&xobject->fscache,

		(enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);

	_leave(" = -ETIMEDOUT");

	return -ETIMEDOUT;

}
@@ -336,7 +338,7 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache, 
try_again:

	/* first step is to make up a grave dentry in the graveyard */

	sprintf(nbuffer, "%08x%08x",

		(uint32_t) get_seconds(),

		(uint32_t) ktime_get_real_seconds(),

		(uint32_t) atomic_inc_return(&cache->gravecounter));



	/* do the multiway lock magic */

fs/cachefiles/rdwr.c

+6 −3
Original line number Diff line number Diff line
@@ -535,7 +535,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object, 
					    netpage->index, cachefiles_gfp);

		if (ret < 0) {

			if (ret == -EEXIST) {

				put_page(backpage);

				backpage = NULL;

				put_page(netpage);

				netpage = NULL;

				fscache_retrieval_complete(op, 1);

				continue;

			}
@@ -608,7 +611,10 @@ static int cachefiles_read_backing_file(struct cachefiles_object *object, 
					    netpage->index, cachefiles_gfp);

		if (ret < 0) {

			if (ret == -EEXIST) {

				put_page(backpage);

				backpage = NULL;

				put_page(netpage);

				netpage = NULL;

				fscache_retrieval_complete(op, 1);

				continue;

			}
@@ -962,11 +968,8 @@ void cachefiles_uncache_page(struct fscache_object *_object, struct page *page) 
	__releases(&object->fscache.cookie->lock)

{

	struct cachefiles_object *object;

	struct cachefiles_cache *cache;



	object = container_of(_object, struct cachefiles_object, fscache);

	cache = container_of(object->fscache.cache,

			     struct cachefiles_cache, cache);



	_enter("%p,{%lu}", object, page->index);

fs/cachefiles/xattr.c

+2 −1
Original line number Diff line number Diff line
@@ -135,7 +135,8 @@ int cachefiles_update_object_xattr(struct cachefiles_object *object, 
	struct dentry *dentry = object->dentry;

	int ret;



	ASSERT(dentry);

	if (!dentry)

		return -ESTALE;



	_enter("%p,#%d", object, auxdata->len);

fs/fscache/object.c

+3 −0
Original line number Diff line number Diff line
@@ -730,6 +730,9 @@ static const struct fscache_state *fscache_drop_object(struct fscache_object *ob 


	if (awaken)

		wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);

	if (test_and_clear_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags))

		wake_up_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP);





	/* Prevent a race with our last child, which has to signal EV_CLEARED

	 * before dropping our spinlock.

include/linux/fscache-cache.h

+1 −2
Original line number Diff line number Diff line
@@ -196,8 +196,7 @@ static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op) 
static inline void fscache_retrieval_complete(struct fscache_retrieval *op,

					      int n_pages)

{

	atomic_sub(n_pages, &op->n_pages);

	if (atomic_read(&op->n_pages) <= 0)

	if (atomic_sub_return_relaxed(n_pages, &op->n_pages) <= 0)

		fscache_op_complete(&op->op, false);

}

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