lkml.org 
[lkml]   [2007]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subjectpatch sysfs-store-sysfs-inode-nrs-in-s_ino-to-avoid-readdir-oopses.patch queued to -stable tree
From
Date

This is a note to let you know that we have just queued up the patch titled

Subject: sysfs: store sysfs inode nrs in s_ino to avoid readdir oopses

to the 2.6.21-stable tree. Its filename is

sysfs-store-sysfs-inode-nrs-in-s_ino-to-avoid-readdir-oopses.patch

A git repo of this tree can be found at
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary


From stable-bounces@linux.kernel.org Mon May 21 19:34:01 2007
From: Eric Sandeen <sandeen@sandeen.net>
Date: Mon, 21 May 2007 21:32:40 -0500
Subject: sysfs: store sysfs inode nrs in s_ino to avoid readdir oopses
To: Eric Sandeen <sandeen@redhat.com>
Cc: stable@kernel.org, Andrew Morton <akpm@linux-foundation.org>, Tejun Heo <htejun@gmail.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Maneesh Soni <maneesh@in.ibm.com>
Message-ID: <46525648.8050807@sandeen.net>


Backport of
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc1/2.6.22-rc1-mm1/broken-out/gregkh-driver-sysfs-allocate-inode-number-using-ida.patch

For regular files in sysfs, sysfs_readdir wants to traverse
sysfs_dirent->s_dentry->d_inode->i_ino to get to the inode number.
But, the dentry can be reclaimed under memory pressure, and there
is no synchronization with readdir. This patch follows Tejun's
scheme of allocating and storing an inode number in the new s_ino
member of a sysfs_dirent, when dirents are created, and retrieving
it from there for readdir, so that the pointer chain doesn't have
to be traversed.

Tejun's upstream patch uses a new-ish "ida" allocator which brings along
some extra complexity; this -stable patch has a brain-dead incrementing
counter which does not guarantee uniqueness, but because sysfs doesn't
hash inodes as iunique expects, uniqueness wasn't guaranteed today anyway.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

--- linux-2.6.21.orig/fs/sysfs/dir.c
+++ linux-2.6.21/fs/sysfs/dir.c
@@ -30,6 +30,14 @@ static struct dentry_operations sysfs_de
.d_iput = sysfs_d_iput,
};

+static unsigned int sysfs_inode_counter;
+ino_t sysfs_get_inum(void)
+{
+ if (unlikely(sysfs_inode_counter < 3))
+ sysfs_inode_counter = 3;
+ return sysfs_inode_counter++;
+}
+
/*
* Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
*/
@@ -41,6 +49,7 @@ static struct sysfs_dirent * __sysfs_new
if (!sd)
return NULL;

+ sd->s_ino = sysfs_get_inum();
atomic_set(&sd->s_count, 1);
atomic_set(&sd->s_event, 1);
INIT_LIST_HEAD(&sd->s_children);
@@ -509,7 +518,7 @@ static int sysfs_readdir(struct file * f

switch (i) {
case 0:
- ino = dentry->d_inode->i_ino;
+ ino = parent_sd->s_ino;
if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
break;
filp->f_pos++;
@@ -538,10 +547,7 @@ static int sysfs_readdir(struct file * f

name = sysfs_get_name(next);
len = strlen(name);
- if (next->s_dentry)
- ino = next->s_dentry->d_inode->i_ino;
- else
- ino = iunique(sysfs_sb, 2);
+ ino = next->s_ino;

if (filldir(dirent, name, len, filp->f_pos, ino,
dt_type(next)) < 0)
Index: linux-2.6.21/fs/sysfs/inode.c
===================================================================
--- linux-2.6.21.orig/fs/sysfs/inode.c
+++ linux-2.6.21/fs/sysfs/inode.c
@@ -140,6 +140,7 @@ struct inode * sysfs_new_inode(mode_t mo
inode->i_mapping->a_ops = &sysfs_aops;
inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
inode->i_op = &sysfs_inode_operations;
+ inode->i_ino = sd->s_ino;
lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);

if (sd->s_iattr) {
Index: linux-2.6.21/fs/sysfs/mount.c
===================================================================
--- linux-2.6.21.orig/fs/sysfs/mount.c
+++ linux-2.6.21/fs/sysfs/mount.c
@@ -33,6 +33,7 @@ static struct sysfs_dirent sysfs_root =
.s_element = NULL,
.s_type = SYSFS_ROOT,
.s_iattr = NULL,
+ .s_ino = 1,
};

static void sysfs_clear_inode(struct inode *inode)
Index: linux-2.6.21/fs/sysfs/sysfs.h
===================================================================
--- linux-2.6.21.orig/fs/sysfs/sysfs.h
+++ linux-2.6.21/fs/sysfs/sysfs.h
@@ -5,6 +5,7 @@ struct sysfs_dirent {
void * s_element;
int s_type;
umode_t s_mode;
+ ino_t s_ino;
struct dentry * s_dentry;
struct iattr * s_iattr;
atomic_t s_event;
_______________________________________________
stable mailing list
stable@linux.kernel.org
http://linux.kernel.org/mailman/listinfo/stable

Patches currently in stable-queue which might be from sandeen@sandeen.net are

queue-2.6.21/sysfs-store-sysfs-inode-nrs-in-s_ino-to-avoid-readdir-oopses.patch
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-06-06 21:53    [W:0.093 / U:0.804 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site