This is a note to let you know that I've just added the patch titled
gfs2: Clean up function may_grant
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
gfs2-clean-up-function-may_grant.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Apr 29 11:07:48 AM CEST 2022
From: Anand Jain <anand.jain@xxxxxxxxxx>
Date: Fri, 15 Apr 2022 06:28:43 +0800
Subject: gfs2: Clean up function may_grant
To: stable@xxxxxxxxxxxxxxx
Cc: linux-btrfs@xxxxxxxxxxxxxxx, Andreas Gruenbacher <agruenba@xxxxxxxxxx>, Anand Jain <anand.jain@xxxxxxxxxx>
Message-ID: <16061e1d0b15ee024905913510b9569e0c5011b4.1649951733.git.anand.jain@xxxxxxxxxx>
From: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
commit 6144464937fe1e6135b13a30502a339d549bf093 upstream
Pass the first current glock holder into function may_grant and
deobfuscate the logic there.
While at it, switch from BUG_ON to GLOCK_BUG_ON in may_grant. To make
that build cleanly, de-constify the may_grant arguments.
We're now using function find_first_holder in do_promote, so move the
function's definition above do_promote.
Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/gfs2/glock.c | 119 ++++++++++++++++++++++++++++++++------------------------
1 file changed, 69 insertions(+), 50 deletions(-)
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -301,46 +301,59 @@ void gfs2_glock_put(struct gfs2_glock *g
}
/**
- * may_grant - check if its ok to grant a new lock
+ * may_grant - check if it's ok to grant a new lock
* @gl: The glock
+ * @current_gh: One of the current holders of @gl
* @gh: The lock request which we wish to grant
*
- * Returns: true if its ok to grant the lock
+ * With our current compatibility rules, if a glock has one or more active
+ * holders (HIF_HOLDER flag set), any of those holders can be passed in as
+ * @current_gh; they are all the same as far as compatibility with the new @gh
+ * goes.
+ *
+ * Returns true if it's ok to grant the lock.
*/
-static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
-{
- const struct gfs2_holder *gh_head = list_first_entry(&gl->gl_holders, const struct gfs2_holder, gh_list);
+static inline bool may_grant(struct gfs2_glock *gl,
+ struct gfs2_holder *current_gh,
+ struct gfs2_holder *gh)
+{
+ if (current_gh) {
+ GLOCK_BUG_ON(gl, !test_bit(HIF_HOLDER, ¤t_gh->gh_iflags));
+
+ switch(current_gh->gh_state) {
+ case LM_ST_EXCLUSIVE:
+ /*
+ * Here we make a special exception to grant holders
+ * who agree to share the EX lock with other holders
+ * who also have the bit set. If the original holder
+ * has the LM_FLAG_NODE_SCOPE bit set, we grant more
+ * holders with the bit set.
+ */
+ return gh->gh_state == LM_ST_EXCLUSIVE &&
+ (current_gh->gh_flags & LM_FLAG_NODE_SCOPE) &&
+ (gh->gh_flags & LM_FLAG_NODE_SCOPE);
- if (gh != gh_head) {
- /**
- * Here we make a special exception to grant holders who agree
- * to share the EX lock with other holders who also have the
- * bit set. If the original holder has the LM_FLAG_NODE_SCOPE bit
- * is set, we grant more holders with the bit set.
- */
- if (gh_head->gh_state == LM_ST_EXCLUSIVE &&
- (gh_head->gh_flags & LM_FLAG_NODE_SCOPE) &&
- gh->gh_state == LM_ST_EXCLUSIVE &&
- (gh->gh_flags & LM_FLAG_NODE_SCOPE))
- return 1;
- if ((gh->gh_state == LM_ST_EXCLUSIVE ||
- gh_head->gh_state == LM_ST_EXCLUSIVE))
- return 0;
+ case LM_ST_SHARED:
+ case LM_ST_DEFERRED:
+ return gh->gh_state == current_gh->gh_state;
+
+ default:
+ return false;
+ }
}
+
if (gl->gl_state == gh->gh_state)
- return 1;
+ return true;
if (gh->gh_flags & GL_EXACT)
- return 0;
+ return false;
if (gl->gl_state == LM_ST_EXCLUSIVE) {
- if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
- return 1;
- if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
- return 1;
+ return gh->gh_state == LM_ST_SHARED ||
+ gh->gh_state == LM_ST_DEFERRED;
}
- if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
- return 1;
- return 0;
+ if (gh->gh_flags & LM_FLAG_ANY)
+ return gl->gl_state != LM_ST_UNLOCKED;
+ return false;
}
static void gfs2_holder_wake(struct gfs2_holder *gh)
@@ -381,6 +394,24 @@ static void do_error(struct gfs2_glock *
}
/**
+ * find_first_holder - find the first "holder" gh
+ * @gl: the glock
+ */
+
+static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
+{
+ struct gfs2_holder *gh;
+
+ if (!list_empty(&gl->gl_holders)) {
+ gh = list_first_entry(&gl->gl_holders, struct gfs2_holder,
+ gh_list);
+ if (test_bit(HIF_HOLDER, &gh->gh_iflags))
+ return gh;
+ }
+ return NULL;
+}
+
+/**
* do_promote - promote as many requests as possible on the current queue
* @gl: The glock
*
@@ -393,14 +424,15 @@ __releases(&gl->gl_lockref.lock)
__acquires(&gl->gl_lockref.lock)
{
const struct gfs2_glock_operations *glops = gl->gl_ops;
- struct gfs2_holder *gh, *tmp;
+ struct gfs2_holder *gh, *tmp, *first_gh;
int ret;
restart:
+ first_gh = find_first_holder(gl);
list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
if (test_bit(HIF_HOLDER, &gh->gh_iflags))
continue;
- if (may_grant(gl, gh)) {
+ if (may_grant(gl, first_gh, gh)) {
if (gh->gh_list.prev == &gl->gl_holders &&
glops->go_lock) {
spin_unlock(&gl->gl_lockref.lock);
@@ -723,23 +755,6 @@ out:
}
/**
- * find_first_holder - find the first "holder" gh
- * @gl: the glock
- */
-
-static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
-{
- struct gfs2_holder *gh;
-
- if (!list_empty(&gl->gl_holders)) {
- gh = list_first_entry(&gl->gl_holders, struct gfs2_holder, gh_list);
- if (test_bit(HIF_HOLDER, &gh->gh_iflags))
- return gh;
- }
- return NULL;
-}
-
-/**
* run_queue - do all outstanding tasks related to a glock
* @gl: The glock in question
* @nonblock: True if we must not block in run_queue
@@ -1354,8 +1369,12 @@ __acquires(&gl->gl_lockref.lock)
GLOCK_BUG_ON(gl, true);
if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
- if (test_bit(GLF_LOCK, &gl->gl_flags))
- try_futile = !may_grant(gl, gh);
+ if (test_bit(GLF_LOCK, &gl->gl_flags)) {
+ struct gfs2_holder *first_gh;
+
+ first_gh = find_first_holder(gl);
+ try_futile = !may_grant(gl, first_gh, gh);
+ }
if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
goto fail;
}
Patches currently in stable-queue which might be from anand.jain@xxxxxxxxxx are
queue-5.15/gup-turn-fault_in_pages_-readable-writeable-into-fault_in_-readable-writeable.patch
queue-5.15/iov_iter-introduce-nofault-flag-to-disable-page-faults.patch
queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-direct-i-o.patch
queue-5.15/iomap-support-partial-direct-i-o-on-user-copy-failures.patch
queue-5.15/mm-gup-make-fault_in_safe_writeable-use-fixup_user_fault.patch
queue-5.15/gfs2-add-wrapper-for-iomap_file_buffered_write.patch
queue-5.15/gup-introduce-foll_nofault-flag-to-disable-page-faults.patch
queue-5.15/iov_iter-introduce-fault_in_iov_iter_writeable.patch
queue-5.15/gfs2-fix-mmap-page-fault-deadlocks-for-buffered-i-o.patch
queue-5.15/btrfs-fallback-to-blocking-mode-when-doing-async-dio-over-multiple-extents.patch
queue-5.15/gfs2-clean-up-function-may_grant.patch
queue-5.15/btrfs-fix-deadlock-due-to-page-faults-during-direct-io-reads-and-writes.patch
queue-5.15/iov_iter-turn-iov_iter_fault_in_readable-into-fault_in_iov_iter_readable.patch
queue-5.15/gfs2-move-the-inode-glock-locking-to-gfs2_file_buffered_write.patch
queue-5.15/gfs2-introduce-flag-for-glock-holder-auto-demotion.patch
queue-5.15/iomap-fix-iomap_dio_rw-return-value-for-user-copies.patch
queue-5.15/gfs2-eliminate-ip-i_gh.patch
queue-5.15/iomap-add-done_before-argument-to-iomap_dio_rw.patch
