Commit e5524c2a authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fscache-fixes-20220708' of... 

Merge tag 'fscache-fixes-20220708' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull fscache fixes from David Howells:

 - Fix a check in fscache_wait_on_volume_collision() in which the
   polarity is reversed. It should complain if a volume is still marked
   acquisition-pending after 20s, but instead complains if the mark has
   been cleared (ie. the condition has cleared).

   Also switch an open-coded test of the ACQUIRE_PENDING volume flag to
   use the helper function for consistency.

 - Not a fix per se, but neaten the code by using a helper to check for
   the DROPPED state.

 - Fix cachefiles's support for erofs to only flush requests associated
   with a released control file, not all requests.

 - Fix a race between one process invalidating an object in the cache
   and another process trying to look it up.

* tag 'fscache-fixes-20220708' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  fscache: Fix invalidation/lookup race
  cachefiles: narrow the scope of flushed requests when releasing fd
  fscache: Introduce fscache_cookie_is_dropped()
  fscache: Fix if condition in fscache_wait_on_volume_collision()
parents 525496a0 85e4ea10

fs/cachefiles/ondemand.c

+2 −1
Original line number Diff line number Diff line
@@ -21,7 +21,8 @@ static int cachefiles_ondemand_fd_release(struct inode *inode, 
	 * anon_fd.

	 */

	xas_for_each(&xas, req, ULONG_MAX) {

		if (req->msg.opcode == CACHEFILES_OP_READ) {

		if (req->msg.object_id == object_id &&

		    req->msg.opcode == CACHEFILES_OP_READ) {

			req->error = -EIO;

			complete(&req->done);

			xas_store(&xas, NULL);

fs/fscache/cookie.c

+22 −4
Original line number Diff line number Diff line
@@ -372,17 +372,22 @@ static struct fscache_cookie *fscache_alloc_cookie( 
	return NULL;

}



static inline bool fscache_cookie_is_dropped(struct fscache_cookie *cookie)

{

	return READ_ONCE(cookie->state) == FSCACHE_COOKIE_STATE_DROPPED;

}



static void fscache_wait_on_collision(struct fscache_cookie *candidate,

				      struct fscache_cookie *wait_for)

{

	enum fscache_cookie_state *statep = &wait_for->state;



	wait_var_event_timeout(statep, READ_ONCE(*statep) == FSCACHE_COOKIE_STATE_DROPPED,

	wait_var_event_timeout(statep, fscache_cookie_is_dropped(wait_for),

			       20 * HZ);

	if (READ_ONCE(*statep) != FSCACHE_COOKIE_STATE_DROPPED) {

	if (!fscache_cookie_is_dropped(wait_for)) {

		pr_notice("Potential collision c=%08x old: c=%08x",

			  candidate->debug_id, wait_for->debug_id);

		wait_var_event(statep, READ_ONCE(*statep) == FSCACHE_COOKIE_STATE_DROPPED);

		wait_var_event(statep, fscache_cookie_is_dropped(wait_for));

	}

}
@@ -517,7 +522,14 @@ static void fscache_perform_lookup(struct fscache_cookie *cookie) 
	}



	fscache_see_cookie(cookie, fscache_cookie_see_active);

	fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);

	spin_lock(&cookie->lock);

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

		__fscache_set_cookie_state(cookie,

					   FSCACHE_COOKIE_STATE_INVALIDATING);

	else

		__fscache_set_cookie_state(cookie, FSCACHE_COOKIE_STATE_ACTIVE);

	spin_unlock(&cookie->lock);

	wake_up_cookie_state(cookie);

	trace = fscache_access_lookup_cookie_end;



out:
@@ -752,6 +764,9 @@ static void fscache_cookie_state_machine(struct fscache_cookie *cookie) 
			spin_lock(&cookie->lock);

		}



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

			fscache_end_cookie_access(cookie, fscache_access_invalidate_cookie_end);



		switch (state) {

		case FSCACHE_COOKIE_STATE_RELINQUISHING:

			fscache_see_cookie(cookie, fscache_cookie_see_relinquish);
@@ -1048,6 +1063,9 @@ void __fscache_invalidate(struct fscache_cookie *cookie, 
		return;



	case FSCACHE_COOKIE_STATE_LOOKING_UP:

		__fscache_begin_cookie_access(cookie, fscache_access_invalidate_cookie);

		set_bit(FSCACHE_COOKIE_DO_INVALIDATE, &cookie->flags);

		fallthrough;

	case FSCACHE_COOKIE_STATE_CREATING:

		spin_unlock(&cookie->lock);

		_leave(" [look %x]", cookie->inval_counter);

fs/fscache/volume.c

+2 −2
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ static void fscache_wait_on_volume_collision(struct fscache_volume *candidate, 
{

	wait_var_event_timeout(&candidate->flags,

			       !fscache_is_acquire_pending(candidate), 20 * HZ);

	if (!fscache_is_acquire_pending(candidate)) {

	if (fscache_is_acquire_pending(candidate)) {

		pr_notice("Potential volume collision new=%08x old=%08x",

			  candidate->debug_id, collidee_debug_id);

		fscache_stat(&fscache_n_volumes_collision);
@@ -182,7 +182,7 @@ static bool fscache_hash_volume(struct fscache_volume *candidate) 
	hlist_bl_add_head(&candidate->hash_link, h);

	hlist_bl_unlock(h);



	if (test_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags))

	if (fscache_is_acquire_pending(candidate))

		fscache_wait_on_volume_collision(candidate, collidee_debug_id);

	return true;

include/linux/fscache.h

+1 −0
Original line number Diff line number Diff line
@@ -130,6 +130,7 @@ struct fscache_cookie { 
#define FSCACHE_COOKIE_DO_PREP_TO_WRITE	12		/* T if cookie needs write preparation */

#define FSCACHE_COOKIE_HAVE_DATA	13		/* T if this cookie has data stored */

#define FSCACHE_COOKIE_IS_HASHED	14		/* T if this cookie is hashed */

#define FSCACHE_COOKIE_DO_INVALIDATE	15		/* T if cookie needs invalidation */



	enum fscache_cookie_state	state;

	u8				advice;		/* FSCACHE_ADV_* */