Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6:
  quota: Fix deadlock during path resolution

6 files changed, 51 insertions, 80 deletions

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 7aa767d4f06f..85c8cc8f2473 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -754,7 +754,7 @@ static int ext3_release_dquot(struct dquot *dquot);
 static int ext3_mark_dquot_dirty(struct dquot *dquot);
 static int ext3_write_info(struct super_block *sb, int type);
 static int ext3_quota_on(struct super_block *sb, int type, int format_id,
-                                char *path);
+                         struct path *path);
 static int ext3_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext3_quota_read(struct super_block *sb, int type, char *data,
                                size_t len, loff_t off);
@@ -2877,27 +2877,20 @@ static int ext3_quota_on_mount(struct super_block *sb, int type)
  * Standard function to be called on quota_on
  */
 static int ext3_quota_on(struct super_block *sb, int type, int format_id,
-                         char *name)
+                         struct path *path)
 {
         int err;
-        struct path path;
 
         if (!test_opt(sb, QUOTA))
                 return -EINVAL;
 
-        err = kern_path(name, LOOKUP_FOLLOW, &path);
-        if (err)
-                return err;
-
         /* Quotafile not on the same filesystem? */
-        if (path.mnt->mnt_sb != sb) {
-                path_put(&path);
+        if (path->mnt->mnt_sb != sb)
                 return -EXDEV;
-        }
         /* Journaling quota? */
         if (EXT3_SB(sb)->s_qf_names[type]) {
                 /* Quotafile not of fs root? */
-                if (path.dentry->d_parent != sb->s_root)
+                if (path->dentry->d_parent != sb->s_root)
                         ext3_msg(sb, KERN_WARNING,
                                 "warning: Quota file not on filesystem root. "
                                 "Journaled quota will not work.");
@@ -2907,7 +2900,7 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id,
          * When we journal data on quota file, we have to flush journal to see
          * all updates to the file when we bypass pagecache...
          */
-        if (ext3_should_journal_data(path.dentry->d_inode)) {
+        if (ext3_should_journal_data(path->dentry->d_inode)) {
                 /*
                  * We don't need to lock updates but journal_flush() could
                  * otherwise be livelocked...
@@ -2915,15 +2908,11 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id,
                 journal_lock_updates(EXT3_SB(sb)->s_journal);
                 err = journal_flush(EXT3_SB(sb)->s_journal);
                 journal_unlock_updates(EXT3_SB(sb)->s_journal);
-                if (err) {
-                        path_put(&path);
+                if (err)
                         return err;
-                }
         }
 
-        err = dquot_quota_on_path(sb, type, format_id, &path);
-        path_put(&path);
-        return err;
+        return dquot_quota_on(sb, type, format_id, path);
 }
 
 /* Read data from quotafile - avoid pagecache and such because we cannot afford
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index cb10a06775e4..48ce561fafac 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1161,7 +1161,7 @@ static int ext4_release_dquot(struct dquot *dquot);
 static int ext4_mark_dquot_dirty(struct dquot *dquot);
 static int ext4_write_info(struct super_block *sb, int type);
 static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-                                char *path);
+                         struct path *path);
 static int ext4_quota_off(struct super_block *sb, int type);
 static int ext4_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
@@ -4558,27 +4558,20 @@ static int ext4_quota_on_mount(struct super_block *sb, int type)
  * Standard function to be called on quota_on
  */
 static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-                         char *name)
+                         struct path *path)
 {
         int err;
-        struct path path;
 
         if (!test_opt(sb, QUOTA))
                 return -EINVAL;
 
-        err = kern_path(name, LOOKUP_FOLLOW, &path);
-        if (err)
-                return err;
-
         /* Quotafile not on the same filesystem? */
-        if (path.mnt->mnt_sb != sb) {
-                path_put(&path);
+        if (path->mnt->mnt_sb != sb)
                 return -EXDEV;
-        }
         /* Journaling quota? */
         if (EXT4_SB(sb)->s_qf_names[type]) {
                 /* Quotafile not in fs root? */
-                if (path.dentry->d_parent != sb->s_root)
+                if (path->dentry->d_parent != sb->s_root)
                         ext4_msg(sb, KERN_WARNING,
                                 "Quota file not on filesystem root. "
                                 "Journaled quota will not work");
@@ -4589,7 +4582,7 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
          * all updates to the file when we bypass pagecache...
          */
         if (EXT4_SB(sb)->s_journal &&
-            ext4_should_journal_data(path.dentry->d_inode)) {
+            ext4_should_journal_data(path->dentry->d_inode)) {
                 /*
                  * We don't need to lock updates but journal_flush() could
                  * otherwise be livelocked...
@@ -4597,15 +4590,11 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
                 jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
                 err = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
                 jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
-                if (err) {
-                        path_put(&path);
+                if (err)
                         return err;
-                }
         }
 
-        err = dquot_quota_on_path(sb, type, format_id, &path);
-        path_put(&path);
-        return err;
+        return dquot_quota_on(sb, type, format_id, path);
 }
 
 static int ext4_quota_off(struct super_block *sb, int type)
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 06d1f749ca89..38f986d2447e 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -993,8 +993,7 @@ static void ocfs2_disable_quotas(struct ocfs2_super *osb)
 }
 
 /* Handle quota on quotactl */
-static int ocfs2_quota_on(struct super_block *sb, int type, int format_id,
-                          char *path)
+static int ocfs2_quota_on(struct super_block *sb, int type, int format_id)
 {
         unsigned int feature[MAXQUOTAS] = { OCFS2_FEATURE_RO_COMPAT_USRQUOTA,
                                              OCFS2_FEATURE_RO_COMPAT_GRPQUOTA};
@@ -1013,7 +1012,7 @@ static int ocfs2_quota_off(struct super_block *sb, int type)
 }
 
 static const struct quotactl_ops ocfs2_quotactl_ops = {
-        .quota_on       = ocfs2_quota_on,
+        .quota_on_meta  = ocfs2_quota_on,
         .quota_off      = ocfs2_quota_off,
         .quota_sync     = dquot_quota_sync,
         .get_info       = dquot_get_dqinfo,
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 84becd3e4772..a2a622e079f0 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2189,8 +2189,8 @@ int dquot_resume(struct super_block *sb, int type)
 }
 EXPORT_SYMBOL(dquot_resume);
 
-int dquot_quota_on_path(struct super_block *sb, int type, int format_id,
-                      struct path *path)
+int dquot_quota_on(struct super_block *sb, int type, int format_id,
+                   struct path *path)
 {
         int error = security_quota_on(path->dentry);
         if (error)
@@ -2204,20 +2204,6 @@ int dquot_quota_on_path(struct super_block *sb, int type, int format_id,
                                              DQUOT_LIMITS_ENABLED);
         return error;
 }
-EXPORT_SYMBOL(dquot_quota_on_path);
-
-int dquot_quota_on(struct super_block *sb, int type, int format_id, char *name)
-{
-        struct path path;
-        int error;
-
-        error = kern_path(name, LOOKUP_FOLLOW, &path);
-        if (!error) {
-                error = dquot_quota_on_path(sb, type, format_id, &path);
-                path_put(&path);
-        }
-        return error;
-}
 EXPORT_SYMBOL(dquot_quota_on);
 
 /*
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index b299961e1edb..b34bdb25490c 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -64,18 +64,15 @@ static int quota_sync_all(int type)
 }
 
 static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
-                         void __user *addr)
+                         struct path *path)
 {
-        char *pathname;
-        int ret = -ENOSYS;
-
-        pathname = getname(addr);
-        if (IS_ERR(pathname))
-                return PTR_ERR(pathname);
-        if (sb->s_qcop->quota_on)
-                ret = sb->s_qcop->quota_on(sb, type, id, pathname);
-        putname(pathname);
-        return ret;
+        if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
+                return -ENOSYS;
+        if (sb->s_qcop->quota_on_meta)
+                return sb->s_qcop->quota_on_meta(sb, type, id);
+        if (IS_ERR(path))
+                return PTR_ERR(path);
+        return sb->s_qcop->quota_on(sb, type, id, path);
 }
 
 static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
@@ -241,7 +238,7 @@ static int quota_getxquota(struct super_block *sb, int type, qid_t id,
 
 /* Copy parameters and call proper function */
 static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
-                       void __user *addr)
+                       void __user *addr, struct path *path)
 {
         int ret;
 
@@ -256,7 +253,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 
         switch (cmd) {
         case Q_QUOTAON:
-                return quota_quotaon(sb, type, cmd, id, addr);
+                return quota_quotaon(sb, type, cmd, id, path);
         case Q_QUOTAOFF:
                 if (!sb->s_qcop->quota_off)
                         return -ENOSYS;
@@ -335,6 +332,7 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
 {
         uint cmds, type;
         struct super_block *sb = NULL;
+        struct path path, *pathp = NULL;
         int ret;
 
         cmds = cmd >> SUBCMDSHIFT;
@@ -351,12 +349,27 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
                 return -ENODEV;
         }
 
+        /*
+         * Path for quotaon has to be resolved before grabbing superblock
+         * because that gets s_umount sem which is also possibly needed by path
+         * resolution (think about autofs) and thus deadlocks could arise.
+         */
+        if (cmds == Q_QUOTAON) {
+                ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW, &path);
+                if (ret)
+                        pathp = ERR_PTR(ret);
+                else
+                        pathp = &path;
+        }
+
         sb = quotactl_block(special);
         if (IS_ERR(sb))
                 return PTR_ERR(sb);
 
-        ret = do_quotactl(sb, type, cmds, id, addr);
+        ret = do_quotactl(sb, type, cmds, id, addr, pathp);
 
         drop_super(sb);
+        if (pathp && !IS_ERR(pathp))
+                path_put(pathp);
         return ret;
 }
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 2575682a9ead..0aab04f46827 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -632,7 +632,7 @@ static int reiserfs_acquire_dquot(struct dquot *);
 static int reiserfs_release_dquot(struct dquot *);
 static int reiserfs_mark_dquot_dirty(struct dquot *);
 static int reiserfs_write_info(struct super_block *, int);
-static int reiserfs_quota_on(struct super_block *, int, int, char *);
+static int reiserfs_quota_on(struct super_block *, int, int, struct path *);
 
 static const struct dquot_operations reiserfs_quota_operations = {
         .write_dquot = reiserfs_write_dquot,
@@ -2048,25 +2048,21 @@ static int reiserfs_quota_on_mount(struct super_block *sb, int type)
  * Standard function to be called on quota_on
  */
 static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
-                             char *name)
+                             struct path *path)
 {
         int err;
-        struct path path;
         struct inode *inode;
         struct reiserfs_transaction_handle th;
 
         if (!(REISERFS_SB(sb)->s_mount_opt & (1 << REISERFS_QUOTA)))
                 return -EINVAL;
 
-        err = kern_path(name, LOOKUP_FOLLOW, &path);
-        if (err)
-                return err;
         /* Quotafile not on the same filesystem? */
-        if (path.mnt->mnt_sb != sb) {
+        if (path->mnt->mnt_sb != sb) {
                 err = -EXDEV;
                 goto out;
         }
-        inode = path.dentry->d_inode;
+        inode = path->dentry->d_inode;
         /* We must not pack tails for quota files on reiserfs for quota IO to work */
         if (!(REISERFS_I(inode)->i_flags & i_nopack_mask)) {
                 err = reiserfs_unpack(inode, NULL);
@@ -2082,7 +2078,7 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
         /* Journaling quota? */
         if (REISERFS_SB(sb)->s_qf_names[type]) {
                 /* Quotafile not of fs root? */
-                if (path.dentry->d_parent != sb->s_root)
+                if (path->dentry->d_parent != sb->s_root)
                         reiserfs_warning(sb, "super-6521",
                                  "Quota file not on filesystem root. "
                                  "Journalled quota will not work.");
@@ -2101,9 +2097,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id,
                 if (err)
                         goto out;
         }
-        err = dquot_quota_on_path(sb, type, format_id, &path);
+        err = dquot_quota_on(sb, type, format_id, path);
 out:
-        path_put(&path);
         return err;
 }