Fix autofs_expire()

mnt should remain the same for all iterations through the list;
as it is, if we have a busy mount, mnt follows into it and isn't
restored for the next iteration.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 18 insertions, 16 deletions

diff --git a/fs/autofs/dirhash.c b/fs/autofs/dirhash.c
index bf8c8af98004..4eb4d8dfb2f1 100644
--- a/fs/autofs/dirhash.c
+++ b/fs/autofs/dirhash.c
@@ -39,10 +39,12 @@ struct autofs_dir_ent *autofs_expire(struct super_block *sb,
 {
         struct autofs_dirhash *dh = &sbi->dirhash;
         struct autofs_dir_ent *ent;
-        struct dentry *dentry;
         unsigned long timeout = sbi->exp_timeout;
 
         while (1) {
+                struct path path;
+                int umount_ok;
+
                 if ( list_empty(&dh->expiry_head) || sbi->catatonic )
                         return NULL;    /* No entries */
                 /* We keep the list sorted by last_usage and want old stuff */
@@ -57,17 +59,17 @@ struct autofs_dir_ent *autofs_expire(struct super_block *sb,
                         return ent; /* Symlinks are always expirable */
 
                 /* Get the dentry for the autofs subdirectory */
-                dentry = ent->dentry;
+                path.dentry = ent->dentry;
 
-                if ( !dentry ) {
+                if (!path.dentry) {
                         /* Should only happen in catatonic mode */
                         printk("autofs: dentry == NULL but inode range is directory, entry %s\n", ent->name);
                         autofs_delete_usage(ent);
                         continue;
                 }
 
-                if ( !dentry->d_inode ) {
-                        dput(dentry);
+                if (!path.dentry->d_inode) {
+                        dput(path.dentry);
                         printk("autofs: negative dentry on expiry queue: %s\n",
                                ent->name);
                         autofs_delete_usage(ent);
@@ -76,29 +78,29 @@ struct autofs_dir_ent *autofs_expire(struct super_block *sb,
 
                 /* Make sure entry is mounted and unused; note that dentry will
                    point to the mounted-on-top root. */
-                if (!S_ISDIR(dentry->d_inode->i_mode)||!d_mountpoint(dentry)) {
+                if (!S_ISDIR(path.dentry->d_inode->i_mode) ||
+                    !d_mountpoint(path.dentry)) {
                         DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
                         continue;
                 }
-                mntget(mnt);
-                dget(dentry);
-                if (!follow_down(&mnt, &dentry)) {
-                        dput(dentry);
-                        mntput(mnt);
+                path.mnt = mnt;
+                path_get(&path);
+                if (!follow_down(&path.mnt, &path.dentry)) {
+                        path_put(&path);
                         DPRINTK(("autofs: not expirable (not a mounted directory): %s\n", ent->name));
                         continue;
                 }
-                while (d_mountpoint(dentry) && follow_down(&mnt, &dentry))
+                while (d_mountpoint(path.dentry) &&
+                       follow_down(&path.mnt, &path.dentry))
                         ;
-                dput(dentry);
+                umount_ok = may_umount(path.mnt);
+                path_put(&path);
 
-                if ( may_umount(mnt) ) {
-                        mntput(mnt);
+                if (umount_ok) {
                         DPRINTK(("autofs: signaling expire on %s\n", ent->name));
                         return ent; /* Expirable! */
                 }
                 DPRINTK(("autofs: didn't expire due to may_umount: %s\n", ent->name));
-                mntput(mnt);
         }
         return NULL;            /* No expirable entries */
 }