From f8d4f618fed5a4978afada52166bc2efaf7656d1 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 12 Feb 2010 19:22:23 -0800 Subject: sysfs: Serialize updates to the vfs inode The vfs depends upon filesystem methods to update the vfs inode. Sysfs adds to the normal number of places where the vfs inode is updated by also updatng the vfs inode in sysfs_refresh_inode. Typically the inode mutex is used to serialize updates to the vfs inode, but grabbing the inode mutex in sysfs_permission and sysfs_getattr causes deadlocks, because sometimes the vfs calls those operations with the inode mutex held. Therefore sysfs can not use the inode mutex to serial updates to the vfs inode. The sysfs_mutex is acquired in all of the routines where sysfs updates the vfs inode, and with a small change we can consistently protext sysfs vfs inode updates with the sysfs_mutex. To protect the sysfs vfs inode updates with the sysfs_mutex simply requires extending the scope of sysfs_mutex in sysfs_setattr over inode_setattr, and over inode_change_ok (so we have an unchanging inode when we perform the check). Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/inode.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'fs/sysfs/inode.c') diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 6a06a1d1ea7b..0d09f6c6efab 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -111,20 +111,20 @@ int sysfs_setattr(struct dentry *dentry, struct iattr *iattr) if (!sd) return -EINVAL; + mutex_lock(&sysfs_mutex); error = inode_change_ok(inode, iattr); if (error) - return error; + goto out; iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */ error = inode_setattr(inode, iattr); if (error) - return error; + goto out; - mutex_lock(&sysfs_mutex); error = sysfs_sd_setattr(sd, iattr); +out: mutex_unlock(&sysfs_mutex); - return error; } -- cgit v1.2.3 From fac2622bbad4d7e3a32c53e631e018b80ec631dc Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 12 Feb 2010 19:22:27 -0800 Subject: sysfs: Pass super_block to sysfs_get_inode Currently sysfs_get_inode magically returns an inode on sysfs_sb. Make the super_block parameter explicit and the code becomes clearer. Acked-by: Tejun Heo Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 2 +- fs/sysfs/inode.c | 5 +++-- fs/sysfs/mount.c | 2 +- fs/sysfs/sysfs.h | 2 +- 4 files changed, 6 insertions(+), 5 deletions(-) (limited to 'fs/sysfs/inode.c') diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 481fdec09f4e..590717861c7a 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -645,7 +645,7 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry, } /* attach dentry and inode */ - inode = sysfs_get_inode(sd); + inode = sysfs_get_inode(dir->i_sb, sd); if (!inode) { ret = ERR_PTR(-ENOMEM); goto out_unlock; diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 0d09f6c6efab..082daaecac1b 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -283,6 +283,7 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) /** * sysfs_get_inode - get inode for sysfs_dirent + * @sb: super block * @sd: sysfs_dirent to allocate inode for * * Get inode for @sd. If such inode doesn't exist, a new inode @@ -295,11 +296,11 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode) * RETURNS: * Pointer to allocated inode on success, NULL on failure. */ -struct inode * sysfs_get_inode(struct sysfs_dirent *sd) +struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd) { struct inode *inode; - inode = iget_locked(sysfs_sb, sd->s_ino); + inode = iget_locked(sb, sd->s_ino); if (inode && (inode->i_state & I_NEW)) sysfs_init_inode(sd, inode); diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c index 49749955ccaf..89db07e489b0 100644 --- a/fs/sysfs/mount.c +++ b/fs/sysfs/mount.c @@ -54,7 +54,7 @@ static int sysfs_fill_super(struct super_block *sb, void *data, int silent) /* get root inode, initialize and unlock it */ mutex_lock(&sysfs_mutex); - inode = sysfs_get_inode(&sysfs_root); + inode = sysfs_get_inode(sb, &sysfs_root); mutex_unlock(&sysfs_mutex); if (!inode) { pr_debug("sysfs: could not get root inode\n"); diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 5a3192a08442..7593d71d92f8 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -172,7 +172,7 @@ static inline void __sysfs_put(struct sysfs_dirent *sd) /* * inode.c */ -struct inode *sysfs_get_inode(struct sysfs_dirent *sd); +struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd); void sysfs_delete_inode(struct inode *inode); int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr); int sysfs_permission(struct inode *inode, int mask); -- cgit v1.2.3