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Commit 2c463e95 authored by Dave Hansen's avatar Dave Hansen Committed by Al Viro
Browse files

[PATCH] r/o bind mounts: check mnt instead of superblock directly 



If we depend on the inodes for writeability, we will not catch the r/o mounts
when implemented.

This patches uses __mnt_want_write().  It does not guarantee that the mount
will stay writeable after the check.  But, this is OK for one of the checks
because it is just for a printk().

The other two are probably unnecessary and duplicate existing checks in the
VFS.  This won't make them better checks than before, but it will make them
detect r/o mounts.

Acked-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ec82687f

fs/nfs/dir.c

+2 −1
Original line number Diff line number Diff line
@@ -967,7 +967,8 @@ static int is_atomic_open(struct inode *dir, struct nameidata *nd) 
	if (nd->flags & LOOKUP_DIRECTORY)

		return 0;

	/* Are we trying to write to a read only partition? */

	if (IS_RDONLY(dir) && (nd->intent.open.flags & (O_CREAT|O_TRUNC|FMODE_WRITE)))

	if (__mnt_is_readonly(nd->path.mnt) &&

	    (nd->intent.open.flags & (O_CREAT|O_TRUNC|FMODE_WRITE)))

		return 0;

	return 1;

}

fs/nfsd/vfs.c

+3 −2
Original line number Diff line number Diff line
@@ -1912,7 +1912,7 @@ nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp, 
		inode->i_mode,

		IS_IMMUTABLE(inode)?	" immut" : "",

		IS_APPEND(inode)?	" append" : "",

		IS_RDONLY(inode)?	" ro" : "");

		__mnt_is_readonly(exp->ex_path.mnt)?	" ro" : "");

	dprintk("      owner %d/%d user %d/%d\n",

		inode->i_uid, inode->i_gid, current->fsuid, current->fsgid);

#endif
@@ -1923,7 +1923,8 @@ nfsd_permission(struct svc_rqst *rqstp, struct svc_export *exp, 
	 */

	if (!(acc & MAY_LOCAL_ACCESS))

		if (acc & (MAY_WRITE | MAY_SATTR | MAY_TRUNC)) {

			if (exp_rdonly(rqstp, exp) || IS_RDONLY(inode))

			if (exp_rdonly(rqstp, exp) ||

			    __mnt_is_readonly(exp->ex_path.mnt))

				return nfserr_rofs;

			if (/* (acc & MAY_WRITE) && */ IS_IMMUTABLE(inode))

				return nfserr_perm;