Commit 878dabb6 authored May 18, 2020 by Luis Henriques Committed by Ilya Dryomov Jun 01, 2020

ceph: don't return -ESTALE if there's still an open file



Similarly to commit 03f21904 ("ceph: check i_nlink while converting
a file handle to dentry"), this fixes another corner case with
name_to_handle_at/open_by_handle_at.  The issue has been detected by
xfstest generic/467, when doing:

 - name_to_handle_at("/cephfs/myfile")
 - open("/cephfs/myfile")
 - unlink("/cephfs/myfile")
 - sync; sync;
 - drop caches
 - open_by_handle_at()

The call to open_by_handle_at should not fail because the file hasn't been
deleted yet (only unlinked) and we do have a valid handle to it.  -ESTALE
shall be returned only if i_nlink is 0 *and* i_count is 1.

This patch also makes sure we have LINK caps before checking i_nlink.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

parent 53ab8e7c

fs/ceph/export.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -172,9 +172,16 @@ struct inode ceph_lookup_inode(struct super_block sb, u64 ino)
		static struct dentry __fh_to_dentry(struct super_block sb, u64 ino)
		{
		struct inode *inode = __lookup_inode(sb, ino);
		int err;

		if (IS_ERR(inode))
		return ERR_CAST(inode);
		if (inode->i_nlink == 0) {
		/* We need LINK caps to reliably check i_nlink */
		err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
		if (err)
		return ERR_PTR(err);
		/* -ESTALE if inode as been unlinked and no file is open */
		if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) {
		iput(inode);
		return ERR_PTR(-ESTALE);
		}

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