diff options
| -rw-r--r-- | fs/sysfs/dir.c | 22 | ||||
| -rw-r--r-- | fs/sysfs/inode.c | 18 | ||||
| -rw-r--r-- | fs/sysfs/sysfs.h | 1 |
3 files changed, 38 insertions, 3 deletions
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 17a819151b91..c4342a019972 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -13,14 +13,26 @@ #include "sysfs.h" DECLARE_RWSEM(sysfs_rename_sem); +spinlock_t sysfs_lock = SPIN_LOCK_UNLOCKED; static void sysfs_d_iput(struct dentry * dentry, struct inode * inode) { struct sysfs_dirent * sd = dentry->d_fsdata; if (sd) { - BUG_ON(sd->s_dentry != dentry); - sd->s_dentry = NULL; + /* sd->s_dentry is protected with sysfs_lock. This + * allows sysfs_drop_dentry() to dereference it. + */ + spin_lock(&sysfs_lock); + + /* The dentry might have been deleted or another + * lookup could have happened updating sd->s_dentry to + * point the new dentry. Ignore if it isn't pointing + * to this dentry. + */ + if (sd->s_dentry == dentry) + sd->s_dentry = NULL; + spin_unlock(&sysfs_lock); sysfs_put(sd); } iput(inode); @@ -247,7 +259,10 @@ static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry) } dentry->d_fsdata = sysfs_get(sd); + /* protect sd->s_dentry against sysfs_d_iput */ + spin_lock(&sysfs_lock); sd->s_dentry = dentry; + spin_unlock(&sysfs_lock); error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init); if (error) { sysfs_put(sd); @@ -269,7 +284,10 @@ static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry) int err = 0; dentry->d_fsdata = sysfs_get(sd); + /* protect sd->s_dentry against sysfs_d_iput */ + spin_lock(&sysfs_lock); sd->s_dentry = dentry; + spin_unlock(&sysfs_lock); err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink); if (!err) { dentry->d_op = &sysfs_dentry_ops; diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c index 38bbe071cc15..5266eec15f6e 100644 --- a/fs/sysfs/inode.c +++ b/fs/sysfs/inode.c @@ -246,9 +246,23 @@ static inline void orphan_all_buffers(struct inode *node) */ void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent) { - struct dentry * dentry = sd->s_dentry; + struct dentry *dentry = NULL; struct inode *inode; + /* We're not holding a reference to ->s_dentry dentry but the + * field will stay valid as long as sysfs_lock is held. + */ + spin_lock(&sysfs_lock); + spin_lock(&dcache_lock); + + /* dget dentry if it's still alive */ + if (sd->s_dentry && sd->s_dentry->d_inode) + dentry = dget_locked(sd->s_dentry); + + spin_unlock(&dcache_lock); + spin_unlock(&sysfs_lock); + + /* drop dentry */ if (dentry) { spin_lock(&dcache_lock); spin_lock(&dentry->d_lock); @@ -268,6 +282,8 @@ void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent) spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); } + + dput(dentry); } } diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h index 1966e1a0a015..502c949c402d 100644 --- a/fs/sysfs/sysfs.h +++ b/fs/sysfs/sysfs.h @@ -33,6 +33,7 @@ extern const unsigned char * sysfs_get_name(struct sysfs_dirent *sd); extern void sysfs_drop_dentry(struct sysfs_dirent *sd, struct dentry *parent); extern int sysfs_setattr(struct dentry *dentry, struct iattr *iattr); +extern spinlock_t sysfs_lock; extern struct rw_semaphore sysfs_rename_sem; extern struct super_block * sysfs_sb; extern const struct file_operations sysfs_dir_operations; |