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>

diff --git a/fs/autofs/dirhash.c b/fs/autofs/dirhash.c
index bf8c8af980044462ece05e7fc9772d0efb9d6c13..4eb4d8dfb2f183016fbf97139afd92b4e70714f8 100644 (file)
--- 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 */
 }