From: Andreas Gruenbacher <agruenba@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
cluster-devel@redhat.com, linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
Matthew Wilcox <willy@infradead.org>
Subject: [RFC 8/9] gfs2: Add LM_FLAG_OUTER glock holder flag
Date: Mon, 31 May 2021 19:01:22 +0200 [thread overview]
Message-ID: <20210531170123.243771-9-agruenba@redhat.com> (raw)
In-Reply-To: <20210531170123.243771-1-agruenba@redhat.com>
When a glock holder has the LM_FLAG_OUTER flag set, we set the
current_holds_glock() flag upon taking the lock. With that, we
can recognize when trying to take an "inner" glock, and react
accordingly.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
fs/gfs2/glock.c | 12 ++++++++++++
fs/gfs2/glock.h | 13 ++++++++++---
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index d9cb261f55b0..f6cae2ee1c83 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1427,6 +1427,11 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
if (glock_blocked_by_withdraw(gl) && !(gh->gh_flags & LM_FLAG_NOEXP))
return -EIO;
+ if (gh->gh_flags & LM_FLAG_OUTER) {
+ BUG_ON(current_holds_glock());
+ set_current_holds_glock(true);
+ }
+
if (test_bit(GLF_LRU, &gl->gl_flags))
gfs2_glock_remove_from_lru(gl);
@@ -1514,6 +1519,11 @@ void gfs2_glock_dq(struct gfs2_holder *gh)
__gfs2_glock_queue_work(gl, delay);
}
spin_unlock(&gl->gl_lockref.lock);
+
+ if (gh->gh_flags & LM_FLAG_OUTER) {
+ BUG_ON(!current_holds_glock());
+ set_current_holds_glock(false);
+ }
}
void gfs2_glock_dq_wait(struct gfs2_holder *gh)
@@ -2068,6 +2078,8 @@ static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
*p++ = 'p';
if (flags & LM_FLAG_NODE_SCOPE)
*p++ = 'n';
+ if (flags & LM_FLAG_OUTER)
+ *p++ = 'o';
if (flags & GL_ASYNC)
*p++ = 'a';
if (flags & GL_EXACT)
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index f0ef6fd24ba4..8b145269fb14 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -94,6 +94,12 @@ static inline bool gfs2_holder_is_compatible(struct gfs2_holder *gh, int state)
* This holder agrees to share the lock within this node. In other words,
* the glock is held in EX mode according to DLM, but local holders on the
* same node can share it.
+ *
+ * LM_FLAG_OUTER
+ * Use set_current_holds_glock() to indicate when the current task is holding
+ * this "upper" glock, and current_holds_glock() to detect when the current
+ * task is trying to take another glock. Used to prevent deadlocks involving
+ * the inode glock during page faults.
*/
#define LM_FLAG_TRY 0x0001
@@ -102,9 +108,10 @@ static inline bool gfs2_holder_is_compatible(struct gfs2_holder *gh, int state)
#define LM_FLAG_ANY 0x0008
#define LM_FLAG_PRIORITY 0x0010
#define LM_FLAG_NODE_SCOPE 0x0020
-#define GL_ASYNC 0x0040
-#define GL_EXACT 0x0080
-#define GL_SKIP 0x0100
+#define LM_FLAG_OUTER 0x0040
+#define GL_ASYNC 0x0080
+#define GL_EXACT 0x0100
+#define GL_SKIP 0x0200
#define GL_NOCACHE 0x0400
/*
--
2.26.3
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Gruenbacher <agruenba@redhat.com>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [RFC 8/9] gfs2: Add LM_FLAG_OUTER glock holder flag
Date: Mon, 31 May 2021 19:01:22 +0200 [thread overview]
Message-ID: <20210531170123.243771-9-agruenba@redhat.com> (raw)
In-Reply-To: <20210531170123.243771-1-agruenba@redhat.com>
When a glock holder has the LM_FLAG_OUTER flag set, we set the
current_holds_glock() flag upon taking the lock. With that, we
can recognize when trying to take an "inner" glock, and react
accordingly.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
fs/gfs2/glock.c | 12 ++++++++++++
fs/gfs2/glock.h | 13 ++++++++++---
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index d9cb261f55b0..f6cae2ee1c83 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1427,6 +1427,11 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
if (glock_blocked_by_withdraw(gl) && !(gh->gh_flags & LM_FLAG_NOEXP))
return -EIO;
+ if (gh->gh_flags & LM_FLAG_OUTER) {
+ BUG_ON(current_holds_glock());
+ set_current_holds_glock(true);
+ }
+
if (test_bit(GLF_LRU, &gl->gl_flags))
gfs2_glock_remove_from_lru(gl);
@@ -1514,6 +1519,11 @@ void gfs2_glock_dq(struct gfs2_holder *gh)
__gfs2_glock_queue_work(gl, delay);
}
spin_unlock(&gl->gl_lockref.lock);
+
+ if (gh->gh_flags & LM_FLAG_OUTER) {
+ BUG_ON(!current_holds_glock());
+ set_current_holds_glock(false);
+ }
}
void gfs2_glock_dq_wait(struct gfs2_holder *gh)
@@ -2068,6 +2078,8 @@ static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
*p++ = 'p';
if (flags & LM_FLAG_NODE_SCOPE)
*p++ = 'n';
+ if (flags & LM_FLAG_OUTER)
+ *p++ = 'o';
if (flags & GL_ASYNC)
*p++ = 'a';
if (flags & GL_EXACT)
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index f0ef6fd24ba4..8b145269fb14 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -94,6 +94,12 @@ static inline bool gfs2_holder_is_compatible(struct gfs2_holder *gh, int state)
* This holder agrees to share the lock within this node. In other words,
* the glock is held in EX mode according to DLM, but local holders on the
* same node can share it.
+ *
+ * LM_FLAG_OUTER
+ * Use set_current_holds_glock() to indicate when the current task is holding
+ * this "upper" glock, and current_holds_glock() to detect when the current
+ * task is trying to take another glock. Used to prevent deadlocks involving
+ * the inode glock during page faults.
*/
#define LM_FLAG_TRY 0x0001
@@ -102,9 +108,10 @@ static inline bool gfs2_holder_is_compatible(struct gfs2_holder *gh, int state)
#define LM_FLAG_ANY 0x0008
#define LM_FLAG_PRIORITY 0x0010
#define LM_FLAG_NODE_SCOPE 0x0020
-#define GL_ASYNC 0x0040
-#define GL_EXACT 0x0080
-#define GL_SKIP 0x0100
+#define LM_FLAG_OUTER 0x0040
+#define GL_ASYNC 0x0080
+#define GL_EXACT 0x0100
+#define GL_SKIP 0x0200
#define GL_NOCACHE 0x0400
/*
--
2.26.3
next prev parent reply other threads:[~2021-05-31 17:10 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 17:01 [RFC 0/9] gfs2: handle page faults during read and write Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 1/9] gfs2: Clean up the error handling in gfs2_page_mkwrite Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 2/9] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 3/9] gfs2: Add gfs2_holder_is_compatible helper Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 4/9] gfs2: Fix mmap + page fault deadlocks (part 1) Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-06-01 6:00 ` Linus Torvalds
2021-06-01 6:00 ` [Cluster-devel] " Linus Torvalds
2021-06-02 11:16 ` Andreas Gruenbacher
2021-06-02 11:16 ` [Cluster-devel] " Andreas Gruenbacher
2021-06-11 16:25 ` Al Viro
2021-06-11 16:25 ` [Cluster-devel] " Al Viro
2021-06-12 21:05 ` Al Viro
2021-06-12 21:05 ` [Cluster-devel] " Al Viro
2021-06-12 21:35 ` Al Viro
2021-06-12 21:35 ` [Cluster-devel] " Al Viro
2021-06-13 8:44 ` Steven Whitehouse
2021-06-13 8:44 ` Steven Whitehouse
2021-05-31 17:01 ` [RFC 5/9] iov_iter: Add iov_iter_fault_in_writeable() Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:12 ` Al Viro
2021-05-31 17:12 ` [Cluster-devel] " Al Viro
2021-06-12 21:12 ` Al Viro
2021-06-12 21:12 ` [Cluster-devel] " Al Viro
2021-06-12 21:33 ` Linus Torvalds
2021-06-12 21:33 ` [Cluster-devel] " Linus Torvalds
2021-06-12 21:47 ` Al Viro
2021-06-12 21:47 ` [Cluster-devel] " Al Viro
2021-06-12 23:17 ` Linus Torvalds
2021-06-12 23:17 ` [Cluster-devel] " Linus Torvalds
2021-06-12 23:38 ` Al Viro
2021-06-12 23:38 ` [Cluster-devel] " Al Viro
2021-05-31 17:01 ` [RFC 6/9] gfs2: Add wrappers for accessing journal_info Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 7/9] gfs2: Encode glock holding and retry flags in journal_info Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-05-31 17:01 ` Andreas Gruenbacher [this message]
2021-05-31 17:01 ` [Cluster-devel] [RFC 8/9] gfs2: Add LM_FLAG_OUTER glock holder flag Andreas Gruenbacher
2021-05-31 17:01 ` [RFC 9/9] gfs2: Fix mmap + page fault deadlocks (part 2) Andreas Gruenbacher
2021-05-31 17:01 ` [Cluster-devel] " Andreas Gruenbacher
2021-06-01 5:47 ` Linus Torvalds
2021-06-01 5:47 ` [Cluster-devel] " Linus Torvalds
2021-05-31 17:57 ` [Cluster-devel] [RFC 0/9] gfs2: handle page faults during read and write Linus Torvalds
2021-05-31 20:35 ` Andreas Gruenbacher
2021-05-31 20:35 ` [Cluster-devel] " Andreas Gruenbacher
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