[PATCH] fuse: clean up request size limit checking

Change the way a too large request is handled.  Until now in this case the
device read returned -EINVAL and the operation returned -EIO.

Make it more flexibible by not returning -EINVAL from the read, but restarting
it instead.

Also remove the fixed limit on setxattr data and let the filesystem provide as
large a read buffer as it needs to handle the extended attribute data.

The symbolic link length is already checked by VFS to be less than PATH_MAX,
so the extra check against FUSE_SYMLINK_MAX is not needed.

The check in fuse_create_open() against FUSE_NAME_MAX is not needed, since the
dentry has already been looked up, and hence the name already checked.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 10 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index e5bc3f8eebd0..1afdffdf80db 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -617,6 +617,7 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov,
         struct fuse_copy_state cs;
         unsigned reqsize;
 
+ restart:
         spin_lock(&fuse_lock);
         fc = file->private_data;
         err = -EPERM;
@@ -632,20 +633,25 @@ static ssize_t fuse_dev_readv(struct file *file, const struct iovec *iov,
 
         req = list_entry(fc->pending.next, struct fuse_req, list);
         list_del_init(&req->list);
-        spin_unlock(&fuse_lock);
 
         in = &req->in;
-        reqsize = req->in.h.len;
-        fuse_copy_init(&cs, 1, req, iov, nr_segs);
-        err = -EINVAL;
-        if (iov_length(iov, nr_segs) >= reqsize) {
-                err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
-                if (!err)
-                        err = fuse_copy_args(&cs, in->numargs, in->argpages,
-                                             (struct fuse_arg *) in->args, 0);
+        reqsize = in->h.len;
+        /* If request is too large, reply with an error and restart the read */
+        if (iov_length(iov, nr_segs) < reqsize) {
+                req->out.h.error = -EIO;
+                /* SETXATTR is special, since it may contain too large data */
+                if (in->h.opcode == FUSE_SETXATTR)
+                        req->out.h.error = -E2BIG;
+                request_end(fc, req);
+                goto restart;
         }
+        spin_unlock(&fuse_lock);
+        fuse_copy_init(&cs, 1, req, iov, nr_segs);
+        err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
+        if (!err)
+                err = fuse_copy_args(&cs, in->numargs, in->argpages,
+                                     (struct fuse_arg *) in->args, 0);
         fuse_copy_finish(&cs);
-
         spin_lock(&fuse_lock);
         req->locked = 0;
         if (!err && req->interrupted)