inode numbering: change libfs sb creation routines to avoid collisions with their...

This patch makes it so that simple_fill_super and get_sb_pseudo assign their
root inodes to be number 1.  It also fixes up a couple of callers of
simple_fill_super that were passing in files arrays that had an index at
number 1, and adds a warning for any caller that sends in such an array.

It would have been nice to have made it so that it wasn't possible to make
such a collision, but some callers need to be able to control what inode
number their entries get, so I think this is the best that can be done.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/infiniband/hw/ipath/ipath_fs.c b/drivers/infiniband/hw/ipath/ipath_fs.c
index 036ed1ef17960a5f2e9f5078b4752d91b9fc57a0..ebd5c7bd2cdbec4680163237360ee88b12822b67 100644 (file)
--- a/drivers/infiniband/hw/ipath/ipath_fs.c
+++ b/drivers/infiniband/hw/ipath/ipath_fs.c
@@ -523,7 +523,7 @@ static int ipathfs_fill_super(struct super_block *sb, void *data,
        int ret;
 
        static struct tree_descr files[] = {
-               [1] = {"atomic_stats", &atomic_stats_ops, S_IRUGO},
+               [2] = {"atomic_stats", &atomic_stats_ops, S_IRUGO},
                {""},
        };
 

diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index e6f57990b121650647663f95f33727280cf22c4d..18657f001b43ba8b1393da95cb7b0481910ba937 100644 (file)
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -727,8 +727,8 @@ static const struct super_operations s_ops = {
 static int bm_fill_super(struct super_block * sb, void * data, int silent)
 {
        static struct tree_descr bm_files[] = {
-               [1] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
-               [2] = {"register", &bm_register_operations, S_IWUSR},
+               [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
+               [3] = {"register", &bm_register_operations, S_IWUSR},
                /* last one */ {""}
        };
        int err = simple_fill_super(sb, 0x42494e4d, bm_files);

diff --git a/fs/libfs.c b/fs/libfs.c
index d93842d3c0a0b66943a0491622e0793971d70de5..1247ee90253a96f954e1c0783066afe8889a9afc 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -220,6 +220,12 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
        root = new_inode(s);
        if (!root)
                goto Enomem;
+       /*
+        * since this is the first inode, make it number 1. New inodes created
+        * after this must take care not to collide with it (by passing
+        * max_reserved of 1 to iunique).
+        */
+       root->i_ino = 1;
        root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
        root->i_uid = root->i_gid = 0;
        root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
@@ -360,6 +366,11 @@ int simple_commit_write(struct file *file, struct page *page,
        return 0;
 }
 
+/*
+ * the inodes created here are not hashed. If you use iunique to generate
+ * unique inode values later for this filesystem, then you must take care
+ * to pass it an appropriate max_reserved value to avoid collisions.
+ */
 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
 {
        struct inode *inode;
@@ -376,6 +387,11 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
        inode = new_inode(s);
        if (!inode)
                return -ENOMEM;
+       /*
+        * because the root inode is 1, the files array must not contain an
+        * entry at index 1
+        */
+       inode->i_ino = 1;
        inode->i_mode = S_IFDIR | 0755;
        inode->i_uid = inode->i_gid = 0;
        inode->i_blocks = 0;
@@ -391,6 +407,13 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
        for (i = 0; !files->name || files->name[0]; i++, files++) {
                if (!files->name)
                        continue;
+
+               /* warn if it tries to conflict with the root inode */
+               if (unlikely(i == 1))
+                       printk(KERN_WARNING "%s: %s passed in a files array"
+                               "with an index of 1!\n", __func__,
+                               s->s_type->name);
+
                dentry = d_alloc_name(root, files->name);
                if (!dentry)
                        goto out;