Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input

[linux-2.6-omap-h63xx.git] / fs / sysfs / dir.c

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 85a668680f82af4e550b3b381cf7340419eb7d86..c4342a0199727b19fe832c4eaff371c0c8e1b9ee 100644 (file)
--- 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);
@@ -30,6 +42,14 @@ static struct dentry_operations sysfs_dentry_ops = {
        .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 +61,7 @@ static struct sysfs_dirent * __sysfs_new_dirent(void * element)
        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);
@@ -238,7 +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);
@@ -260,7 +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;
@@ -509,7 +536,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 
        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 +565,7 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 
                                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)