1 files changed, 139 insertions, 30 deletions

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 53dabe8d5b8b..dbb70d5a4882 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -473,6 +473,8 @@ void autofs4_dentry_release(struct dentry *de)
 
                 if (sbi) {
                         spin_lock(&sbi->lookup_lock);
+                        if (!list_empty(&inf->active))
+                                list_del(&inf->active);
                         if (!list_empty(&inf->expiring))
                                 list_del(&inf->expiring);
                         spin_unlock(&sbi->lookup_lock);
@@ -497,6 +499,58 @@ static struct dentry_operations autofs4_dentry_operations = {
         .d_release      = autofs4_dentry_release,
 };
 
+static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
+{
+        unsigned int len = name->len;
+        unsigned int hash = name->hash;
+        const unsigned char *str = name->name;
+        struct list_head *p, *head;
+
+        spin_lock(&dcache_lock);
+        spin_lock(&sbi->lookup_lock);
+        head = &sbi->active_list;
+        list_for_each(p, head) {
+                struct autofs_info *ino;
+                struct dentry *dentry;
+                struct qstr *qstr;
+
+                ino = list_entry(p, struct autofs_info, active);
+                dentry = ino->dentry;
+
+                spin_lock(&dentry->d_lock);
+
+                /* Already gone? */
+                if (atomic_read(&dentry->d_count) == 0)
+                        goto next;
+
+                qstr = &dentry->d_name;
+
+                if (dentry->d_name.hash != hash)
+                        goto next;
+                if (dentry->d_parent != parent)
+                        goto next;
+
+                if (qstr->len != len)
+                        goto next;
+                if (memcmp(qstr->name, str, len))
+                        goto next;
+
+                if (d_unhashed(dentry)) {
+                        dget(dentry);
+                        spin_unlock(&dentry->d_lock);
+                        spin_unlock(&sbi->lookup_lock);
+                        spin_unlock(&dcache_lock);
+                        return dentry;
+                }
+next:
+                spin_unlock(&dentry->d_lock);
+        }
+        spin_unlock(&sbi->lookup_lock);
+        spin_unlock(&dcache_lock);
+
+        return NULL;
+}
+
 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
 {
         unsigned int len = name->len;
@@ -553,7 +607,8 @@ next:
 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 {
         struct autofs_sb_info *sbi;
-        struct dentry *expiring;
+        struct autofs_info *ino;
+        struct dentry *expiring, *unhashed;
         int oz_mode;
 
         DPRINTK("name = %.*s",
@@ -571,12 +626,12 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
 
         expiring = autofs4_lookup_expiring(sbi, dentry->d_parent, &dentry->d_name);
         if (expiring) {
-                struct autofs_info *ino = autofs4_dentry_ino(expiring);
                 /*
                  * If we are racing with expire the request might not
                  * be quite complete but the directory has been removed
                  * so it must have been successful, so just wait for it.
                  */
+                ino = autofs4_dentry_ino(expiring);
                 while (ino && (ino->flags & AUTOFS_INF_EXPIRING)) {
                         DPRINTK("wait for incomplete expire %p name=%.*s",
                                 expiring, expiring->d_name.len,
@@ -591,21 +646,41 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                 dput(expiring);
         }
 
-        /*
-         * Mark the dentry incomplete but don't hash it. We do this
-         * to serialize our inode creation operations (symlink and
-         * mkdir) which prevents deadlock during the callback to
-         * the daemon. Subsequent user space lookups for the same
-         * dentry are placed on the wait queue while the daemon
-         * itself is allowed passage unresticted so the create
-         * operation itself can then hash the dentry. Finally,
-         * we check for the hashed dentry and return the newly
-         * hashed dentry.
-         */
-        dentry->d_op = &autofs4_root_dentry_operations;
+        unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
+        if (unhashed)
+                dentry = unhashed;
+        else {
+                /*
+                 * Mark the dentry incomplete but don't hash it. We do this
+                 * to serialize our inode creation operations (symlink and
+                 * mkdir) which prevents deadlock during the callback to
+                 * the daemon. Subsequent user space lookups for the same
+                 * dentry are placed on the wait queue while the daemon
+                 * itself is allowed passage unresticted so the create
+                 * operation itself can then hash the dentry. Finally,
+                 * we check for the hashed dentry and return the newly
+                 * hashed dentry.
+                 */
+                dentry->d_op = &autofs4_root_dentry_operations;
+
+                /*
+                 * And we need to ensure that the same dentry is used for
+                 * all following lookup calls until it is hashed so that
+                 * the dentry flags are persistent throughout the request.
+                 */
+                ino = autofs4_init_ino(NULL, sbi, 0555);
+                if (!ino)
+                        return ERR_PTR(-ENOMEM);
+
+                dentry->d_fsdata = ino;
+                ino->dentry = dentry;
+
+                spin_lock(&sbi->lookup_lock);
+                list_add(&ino->active, &sbi->active_list);
+                spin_unlock(&sbi->lookup_lock);
 
-        dentry->d_fsdata = NULL;
-        d_instantiate(dentry, NULL);
+                d_instantiate(dentry, NULL);
+        }
 
         if (!oz_mode) {
                 spin_lock(&dentry->d_lock);
@@ -630,12 +705,16 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                         if (sigismember (sigset, SIGKILL) ||
                             sigismember (sigset, SIGQUIT) ||
                             sigismember (sigset, SIGINT)) {
+                            if (unhashed)
+                                dput(unhashed);
                             return ERR_PTR(-ERESTARTNOINTR);
                         }
                 }
-                spin_lock(&dentry->d_lock);
-                dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
-                spin_unlock(&dentry->d_lock);
+                if (!oz_mode) {
+                        spin_lock(&dentry->d_lock);
+                        dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
+                        spin_unlock(&dentry->d_lock);
+                }
         }
 
         /*
@@ -659,9 +738,15 @@ static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, s
                 else
                         dentry = ERR_PTR(-ENOENT);
 
+                if (unhashed)
+                        dput(unhashed);
+
                 return dentry;
         }
 
+        if (unhashed)
+                return unhashed;
+
         return NULL;
 }
 
@@ -682,20 +767,30 @@ static int autofs4_dir_symlink(struct inode *dir,
                 return -EACCES;
 
         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
-        if (ino == NULL)
-                return -ENOSPC;
+        if (!ino)
+                return -ENOMEM;
 
-        ino->size = strlen(symname);
-        ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
+        spin_lock(&sbi->lookup_lock);
+        if (!list_empty(&ino->active))
+                list_del_init(&ino->active);
+        spin_unlock(&sbi->lookup_lock);
 
-        if (cp == NULL) {
-                kfree(ino);
-                return -ENOSPC;
+        cp = kmalloc(ino->size + 1, GFP_KERNEL);
+        if (!cp) {
+                if (!dentry->d_fsdata)
+                        kfree(ino);
+                return -ENOMEM;
         }
 
         strcpy(cp, symname);
 
         inode = autofs4_get_inode(dir->i_sb, ino);
+        if (!inode) {
+                kfree(cp);
+                if (!dentry->d_fsdata)
+                        kfree(ino);
+                return -ENOMEM;
+        }
         d_add(dentry, inode);
 
         if (dir == dir->i_sb->s_root->d_inode)
@@ -711,6 +806,8 @@ static int autofs4_dir_symlink(struct inode *dir,
                 atomic_inc(&p_ino->count);
         ino->inode = inode;
 
+        ino->size = strlen(symname);
+        ino->u.symlink = cp;
         dir->i_mtime = CURRENT_TIME;
 
         return 0;
@@ -755,7 +852,8 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 
         spin_lock(&dcache_lock);
         spin_lock(&sbi->lookup_lock);
-        list_add(&ino->expiring, &sbi->expiring_list);
+        if (list_empty(&ino->expiring))
+                list_add(&ino->expiring, &sbi->expiring_list);
         spin_unlock(&sbi->lookup_lock);
         spin_lock(&dentry->d_lock);
         __d_drop(dentry);
@@ -783,7 +881,8 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
                 return -ENOTEMPTY;
         }
         spin_lock(&sbi->lookup_lock);
-        list_add(&ino->expiring, &sbi->expiring_list);
+        if (list_empty(&ino->expiring))
+                list_add(&ino->expiring, &sbi->expiring_list);
         spin_unlock(&sbi->lookup_lock);
         spin_lock(&dentry->d_lock);
         __d_drop(dentry);
@@ -819,10 +918,20 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
                 dentry, dentry->d_name.len, dentry->d_name.name);
 
         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
-        if (ino == NULL)
-                return -ENOSPC;
+        if (!ino)
+                return -ENOMEM;
+
+        spin_lock(&sbi->lookup_lock);
+        if (!list_empty(&ino->active))
+                list_del_init(&ino->active);
+        spin_unlock(&sbi->lookup_lock);
 
         inode = autofs4_get_inode(dir->i_sb, ino);
+        if (!inode) {
+                if (!dentry->d_fsdata)
+                        kfree(ino);
+                return -ENOMEM;
+        }
         d_add(dentry, inode);
 
         if (dir == dir->i_sb->s_root->d_inode)