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Message-ID: <164364202369.1476539.452557132083658522.stgit@warthog.procyon.org.uk>
Date: Mon, 31 Jan 2022 15:13:43 +0000
From: David Howells <dhowells@...hat.com>
To: Amir Goldstein <amir73il@...il.com>
Cc: Miklos Szeredi <miklos@...redi.hu>, linux-unionfs@...r.kernel.org,
linux-cachefs@...hat.com, dhowells@...hat.com,
Christoph Hellwig <hch@...radead.org>,
Miklos Szeredi <miklos@...redi.hu>,
Jeff Layton <jlayton@...nel.org>,
Alexander Viro <viro@...iv.linux.org.uk>,
torvalds@...ux-foundation.org, linux-unionfs@...r.kernel.org,
linux-cachefs@...hat.com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/5] vfs: Add tracepoints for inode_excl_inuse_trylock/unlock
Add tracepoints for inode_excl_inuse_trylock/unlock() to record successful
and lock, failed lock, successful unlock and unlock when it wasn't locked.
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Amir Goldstein <amir73il@...il.com>
cc: Miklos Szeredi <miklos@...redi.hu>
cc: linux-unionfs@...r.kernel.org
cc: linux-cachefs@...hat.com
---
fs/inode.c | 21 +++++++++++++++++----
fs/overlayfs/super.c | 10 ++++++----
include/linux/fs.h | 9 +++++++--
3 files changed, 30 insertions(+), 10 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 954719f66113..61b93a89853f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -22,6 +22,8 @@
#include <linux/iversion.h>
#include <trace/events/writeback.h>
#include "internal.h"
+#define CREATE_TRACE_POINTS
+#include <trace/events/vfs.h>
/*
* Inode locking rules:
@@ -2409,11 +2411,14 @@ EXPORT_SYMBOL(current_time);
/**
* inode_excl_inuse_trylock - Try to exclusively lock an inode for kernel access
* @dentry: Reference to the inode to be locked
+ * @o: Private reference for the kernel service
+ * @who: Which kernel service is trying to gain the lock
*
* Try to gain exclusive access to an inode for a kernel service, returning
* true if successful.
*/
-bool inode_excl_inuse_trylock(struct dentry *dentry)
+bool inode_excl_inuse_trylock(struct dentry *dentry, unsigned int o,
+ enum inode_excl_inuse_by who)
{
struct inode *inode = d_inode(dentry);
bool locked = false;
@@ -2421,7 +2426,10 @@ bool inode_excl_inuse_trylock(struct dentry *dentry)
spin_lock(&inode->i_lock);
if (!(inode->i_state & I_EXCL_INUSE)) {
inode->i_state |= I_EXCL_INUSE;
+ trace_inode_excl_inuse_lock(inode, o, who);
locked = true;
+ } else {
+ trace_inode_excl_inuse_lock_failed(inode, o, who);
}
spin_unlock(&inode->i_lock);
@@ -2432,18 +2440,23 @@ EXPORT_SYMBOL(inode_excl_inuse_trylock);
/**
* inode_excl_inuse_unlock - Unlock exclusive kernel access to an inode
* @dentry: Reference to the inode to be unlocked
+ * @o: Private reference for the kernel service
*
* Drop exclusive access to an inode for a kernel service. A warning is given
* if the inode was not marked for exclusive access.
*/
-void inode_excl_inuse_unlock(struct dentry *dentry)
+void inode_excl_inuse_unlock(struct dentry *dentry, unsigned int o)
{
if (dentry) {
struct inode *inode = d_inode(dentry);
spin_lock(&inode->i_lock);
- WARN_ON(!(inode->i_state & I_EXCL_INUSE));
- inode->i_state &= ~I_EXCL_INUSE;
+ if (WARN_ON(!(inode->i_state & I_EXCL_INUSE))) {
+ trace_inode_excl_inuse_unlock_bad(inode, o);
+ } else {
+ inode->i_state &= ~I_EXCL_INUSE;
+ trace_inode_excl_inuse_unlock(inode, o);
+ }
spin_unlock(&inode->i_lock);
}
}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 5c3361a2dc7c..6434ae11496d 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -224,10 +224,10 @@ static void ovl_free_fs(struct ovl_fs *ofs)
dput(ofs->indexdir);
dput(ofs->workdir);
if (ofs->workdir_locked)
- inode_excl_inuse_unlock(ofs->workbasedir);
+ inode_excl_inuse_unlock(ofs->workbasedir, 0);
dput(ofs->workbasedir);
if (ofs->upperdir_locked)
- inode_excl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);
+ inode_excl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root, 0);
/* Hack! Reuse ofs->layers as a vfsmount array before freeing it */
mounts = (struct vfsmount **) ofs->layers;
@@ -1239,7 +1239,8 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
if (upper_mnt->mnt_sb->s_flags & SB_NOSEC)
sb->s_flags |= SB_NOSEC;
- if (inode_excl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) {
+ if (inode_excl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root, 0,
+ inode_excl_inuse_by_overlayfs)) {
ofs->upperdir_locked = true;
} else {
err = ovl_report_in_use(ofs, "upperdir");
@@ -1499,7 +1500,8 @@ static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs,
ofs->workbasedir = dget(workpath.dentry);
- if (inode_excl_inuse_trylock(ofs->workbasedir)) {
+ if (inode_excl_inuse_trylock(ofs->workbasedir, 0,
+ inode_excl_inuse_by_overlayfs)) {
ofs->workdir_locked = true;
} else {
err = ovl_report_in_use(ofs, "workdir");
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 4c15e270f1ac..f461883d66a8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2389,8 +2389,13 @@ static inline bool inode_is_dirtytime_only(struct inode *inode)
I_FREEING | I_WILL_FREE)) == I_DIRTY_TIME;
}
-bool inode_excl_inuse_trylock(struct dentry *dentry);
-void inode_excl_inuse_unlock(struct dentry *dentry);
+enum inode_excl_inuse_by {
+ inode_excl_inuse_by_overlayfs,
+};
+
+bool inode_excl_inuse_trylock(struct dentry *dentry, unsigned int o,
+ enum inode_excl_inuse_by who);
+void inode_excl_inuse_unlock(struct dentry *dentry, unsigned int o);
static inline bool inode_is_excl_inuse(struct dentry *dentry)
{
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