From: Andreas Gruenbacher <agruenba@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <djwong@kernel.org>
Cc: Jan Kara <jack@suse.cz>,
Andreas Gruenbacher <agruenba@redhat.com>,
linux-kernel@vger.kernel.org, cluster-devel@redhat.com,
linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] [PATCH v6 07/19] gfs2: Clean up function may_grant
Date: Thu, 19 Aug 2021 21:40:50 +0200 [thread overview]
Message-ID: <20210819194102.1491495-8-agruenba@redhat.com> (raw)
In-Reply-To: <20210819194102.1491495-1-agruenba@redhat.com>
Pass the first current glock holder into function may_grant and
deobfuscate the logic there.
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@redhat.com>
---
fs/gfs2/glock.c | 120 ++++++++++++++++++++++++++++--------------------
1 file changed, 70 insertions(+), 50 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 1f3902ecdded..545b435f55ea 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -301,46 +301,59 @@ void gfs2_glock_put(struct gfs2_glock *gl)
}
/**
- * 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(const struct gfs2_glock *gl,
+ const struct gfs2_holder *current_gh,
+ const struct gfs2_holder *gh)
+{
+ if (current_gh) {
+ BUG_ON(!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)
@@ -380,6 +393,24 @@ static void do_error(struct gfs2_glock *gl, const int ret)
}
}
+/**
+ * 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 +424,16 @@ __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;
+ first_gh = find_first_holder(gl);
+
restart:
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);
@@ -722,23 +755,6 @@ __acquires(&gl->gl_lockref.lock)
spin_lock(&gl->gl_lockref.lock);
}
-/**
- * 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
@@ -1354,8 +1370,12 @@ __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;
}
--
2.26.3
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next prev parent reply other threads:[~2021-08-19 19:41 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-19 19:40 [Ocfs2-devel] [PATCH v6 00/19] gfs2: Fix mmap + page fault deadlocks Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 01/19] iov_iter: Fix iov_iter_get_pages{, _alloc} page fault return value Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 02/19] powerpc/kvm: Fix kvm_use_magic_page Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 03/19] Turn fault_in_pages_{readable, writeable} into fault_in_{readable, writeable} Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 04/19] Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 05/19] iov_iter: Introduce fault_in_iov_iter_writeable Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 06/19] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-08-19 19:40 ` Andreas Gruenbacher [this message]
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 08/19] gfs2: Eliminate vestigial HIF_FIRST Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 09/19] gfs2: Remove redundant check from gfs2_glock_dq Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 10/19] gfs2: Introduce flag for glock holder auto-demotion Andreas Gruenbacher
2021-08-20 9:35 ` [Ocfs2-devel] [Cluster-devel] " Steven Whitehouse
2021-08-20 13:11 ` Bob Peterson
2021-08-20 13:41 ` Steven Whitehouse
2021-08-20 15:22 ` Andreas Gruenbacher
2021-08-23 8:14 ` Steven Whitehouse
2021-08-23 15:18 ` Andreas Gruenbacher
2021-08-23 16:05 ` Matthew Wilcox
2021-08-23 16:36 ` Bob Peterson
2021-08-23 19:12 ` Andreas Gruenbacher
2021-08-24 7:59 ` Steven Whitehouse
2021-08-20 13:17 ` Andreas Gruenbacher
2021-08-20 13:47 ` Steven Whitehouse
2021-08-20 14:43 ` Andreas Grünbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 11/19] gfs2: Move the inode glock locking to gfs2_file_buffered_write Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 12/19] gfs2: Fix mmap + page fault deadlocks for buffered I/O Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 13/19] iomap: Fix iomap_dio_rw return value for user copies Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 14/19] iomap: Support partial direct I/O on user copy failures Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 15/19] iomap: Add done_before argument to iomap_dio_rw Andreas Gruenbacher
2021-08-19 19:40 ` [Ocfs2-devel] [PATCH v6 16/19] gup: Introduce FOLL_NOFAULT flag to disable page faults Andreas Gruenbacher
2021-08-19 19:41 ` [Ocfs2-devel] [PATCH v6 17/19] iov_iter: Introduce nofault " Andreas Gruenbacher
2021-08-19 19:41 ` [Ocfs2-devel] [PATCH v6 18/19] gfs2: Fix mmap + page fault deadlocks for direct I/O Andreas Gruenbacher
2021-08-19 19:41 ` [Ocfs2-devel] [PATCH v6 19/19] gfs2: Eliminate ip->i_gh Andreas Gruenbacher
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