Fix remount races with symlink handling in affs

A couple of fields in affs_sb_info is used in follow_link() and
symlink() for handling AFFS "absolute" symlinks.  Need locking
against affs_remount() updates.

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

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/affs/namei.c b/fs/affs/namei.c
index 960d336ec694..d70bbbac6b7b 100644
--- a/fs/affs/namei.c
+++ b/fs/affs/namei.c
@@ -341,10 +341,13 @@ affs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
         p  = (char *)AFFS_HEAD(bh)->table;
         lc = '/';
         if (*symname == '/') {
+                struct affs_sb_info *sbi = AFFS_SB(sb);
                 while (*symname == '/')
                         symname++;
-                while (AFFS_SB(sb)->s_volume[i])        /* Cannot overflow */
-                        *p++ = AFFS_SB(sb)->s_volume[i++];
+                spin_lock(&sbi->symlink_lock);
+                while (sbi->s_volume[i])        /* Cannot overflow */
+                        *p++ = sbi->s_volume[i++];
+                spin_unlock(&sbi->symlink_lock);
         }
         while (i < maxlen && (c = *symname++)) {
                 if (c == '.' && lc == '/' && *symname == '.' && symname[1] == '/') {