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authorMiklos Szeredi <mszeredi@suse.cz>2012-05-21 19:30:20 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2012-06-01 20:12:02 +0400
commit0ef97dcfce4179a2eba046b855ee2f91d6f1b414 (patch)
treed5a29275a427dafd8fce0131b58f215c6252d3e2 /fs/nfs/file.c
parent16b1c1cd71176ab0a76b26818fbf12db9183ed57 (diff)
downloadlinux-0ef97dcfce4179a2eba046b855ee2f91d6f1b414.tar.xz
nfs: don't open in ->d_revalidate
NFSv4 can't do reliable opens in d_revalidate, since it cannot know whether a mount needs to be followed or not. It does check d_mountpoint() on the dentry, which can result in a weird error if the VFS found that the mount does not in fact need to be followed, e.g.: # mount --bind /mnt/nfs /mnt/nfs-clone # echo something > /mnt/nfs/tmp/bar # echo x > /tmp/file # mount --bind /tmp/file /mnt/nfs-clone/tmp/bar # cat /mnt/nfs/tmp/bar cat: /mnt/nfs/tmp/bar: Not a directory Which should, by any sane filesystem, result in "something" being printed. So instead do the open in f_op->open() and in the unlikely case that the cached dentry turned out to be invalid, drop the dentry and return EOPENSTALE to let the VFS retry. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> CC: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/nfs/file.c')
-rw-r--r--fs/nfs/file.c77
1 files changed, 73 insertions, 4 deletions
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 56311ca5f9f8..a6708e6b438d 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -879,12 +879,81 @@ const struct file_operations nfs_file_operations = {
static int
nfs4_file_open(struct inode *inode, struct file *filp)
{
+ struct nfs_open_context *ctx;
+ struct dentry *dentry = filp->f_path.dentry;
+ struct dentry *parent = NULL;
+ struct inode *dir;
+ unsigned openflags = filp->f_flags;
+ struct iattr attr;
+ int err;
+
+ BUG_ON(inode != dentry->d_inode);
/*
- * NFSv4 opens are handled in d_lookup and d_revalidate. If we get to
- * this point, then something is very wrong
+ * If no cached dentry exists or if it's negative, NFSv4 handled the
+ * opens in ->lookup() or ->create().
+ *
+ * We only get this far for a cached positive dentry. We skipped
+ * revalidation, so handle it here by dropping the dentry and returning
+ * -EOPENSTALE. The VFS will retry the lookup/create/open.
*/
- dprintk("NFS: %s called! inode=%p filp=%p\n", __func__, inode, filp);
- return -ENOTDIR;
+
+ dprintk("NFS: open file(%s/%s)\n",
+ dentry->d_parent->d_name.name,
+ dentry->d_name.name);
+
+ if ((openflags & O_ACCMODE) == 3)
+ openflags--;
+
+ /* We can't create new files here */
+ openflags &= ~(O_CREAT|O_EXCL);
+
+ parent = dget_parent(dentry);
+ dir = parent->d_inode;
+
+ ctx = alloc_nfs_open_context(filp->f_path.dentry, filp->f_mode);
+ err = PTR_ERR(ctx);
+ if (IS_ERR(ctx))
+ goto out;
+
+ attr.ia_valid = ATTR_OPEN;
+ if (openflags & O_TRUNC) {
+ attr.ia_valid |= ATTR_SIZE;
+ attr.ia_size = 0;
+ nfs_wb_all(inode);
+ }
+
+ inode = NFS_PROTO(dir)->open_context(dir, ctx, openflags, &attr);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ switch (err) {
+ case -EPERM:
+ case -EACCES:
+ case -EDQUOT:
+ case -ENOSPC:
+ case -EROFS:
+ goto out_put_ctx;
+ default:
+ goto out_drop;
+ }
+ }
+ iput(inode);
+ if (inode != dentry->d_inode)
+ goto out_drop;
+
+ nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+ nfs_file_set_open_context(filp, ctx);
+ err = 0;
+
+out_put_ctx:
+ put_nfs_open_context(ctx);
+out:
+ dput(parent);
+ return err;
+
+out_drop:
+ d_drop(dentry);
+ err = -EOPENSTALE;
+ goto out_put_ctx;
}
const struct file_operations nfs4_file_operations = {