From: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
The revoke operation cannibalizes the revoked struct inode and removes it from
the inode cache thus forcing subsequent callers to look up the real inode.
Therefore we must make sure that while the revoke operation is in progress
(e.g. flushing dirty pages to disk) no one takes a new reference to the inode
and starts I/O on it.
Cc: Alan Cox <alan@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
---
fs/inode.c | 1 +
fs/namei.c | 15 ++++++++++++++-
include/linux/fs.h | 3 +++
3 files changed, 18 insertions(+), 1 deletion(-)
Index: 2.6/include/linux/fs.h
===================================================================
--- 2.6.orig/include/linux/fs.h 2007-11-23 09:58:11.000000000 +0200
+++ 2.6/include/linux/fs.h 2007-12-14 16:40:50.000000000 +0200
@@ -150,6 +150,7 @@ #define MS_MGC_MSK 0xffff0000
#define S_NOCMTIME 128 /* Do not update file c/mtime */
#define S_SWAPFILE 256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE 512 /* Inode is fs-internal */
+#define S_REVOKE_LOCK 1024 /* Inode is being revoked */
/*
* Note that nosuid etc flags are inode-specific: setting some file-system
@@ -183,6 +184,7 @@ #define MS_MGC_MSK 0xffff0000
#define IS_NOCMTIME(inode) ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode) ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode) ((inode)->i_flags & S_PRIVATE)
+#define IS_REVOKE_LOCKED(inode) ((inode)->i_flags & S_REVOKE_LOCK)
/* the read-only stuff doesn't really belong here, but any other place is
probably as bad and I don't want to create yet another include file. */
@@ -642,6 +644,7 @@ struct inode {
struct list_head inotify_watches; /* watches on this inode */
struct mutex inotify_mutex; /* protects the watches list */
#endif
+ wait_queue_head_t i_revoke_wait;
unsigned long i_state;
unsigned long dirtied_when; /* jiffies of first dirtying */
Index: 2.6/fs/inode.c
===================================================================
--- 2.6.orig/fs/inode.c 2007-10-26 09:36:45.000000000 +0300
+++ 2.6/fs/inode.c 2007-12-14 16:40:50.000000000 +0200
@@ -216,6 +216,7 @@ memset(inode, 0, sizeof(*inode));
INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
i_size_ordered_init(inode);
+ init_waitqueue_head(&inode->i_revoke_wait);
#ifdef CONFIG_INOTIFY
INIT_LIST_HEAD(&inode->inotify_watches);
mutex_init(&inode->inotify_mutex);
Index: 2.6/fs/namei.c
===================================================================
--- 2.6.orig/fs/namei.c 2007-10-26 09:36:48.000000000 +0300
+++ 2.6/fs/namei.c 2007-12-14 16:40:50.000000000 +0200
@@ -785,10 +785,23 @@ static int do_lookup(struct nameidata *n
struct path *path)
{
struct vfsmount *mnt = nd->mnt;
- struct dentry *dentry = __d_lookup(nd->dentry, name);
+ struct dentry *dentry;
+again:
+ dentry = __d_lookup(nd->dentry, name);
if (!dentry)
goto need_lookup;
+
+ if (dentry->d_inode && IS_REVOKE_LOCKED(dentry->d_inode)) {
+ int err;
+
+ err = wait_event_interruptible(dentry->d_inode->i_revoke_wait,
+ !IS_REVOKE_LOCKED(dentry->d_inode));
+ if (err)
+ return err;
+ goto again;
+ }
+
if (dentry->d_op && dentry->d_op->d_revalidate)
goto need_revalidate;
done:
-
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