fuse: fix request limit

The size of struct fuse_req was reduced from 392B to 144B on a non-debug
config, thus the sanitize_global_limit() helper was setting a larger
default limit.  This doesn't really reflect reduction in the memory used by
requests, since the fields removed from fuse_req were added to fuse_args
derived structs; e.g. sizeof(struct fuse_writepages_args) is 248B, thus
resulting in slightly more memory being used for writepage requests
overalll (due to using 256B slabs).

Make the calculatation ignore the size of fuse_req and use the old 392B
value.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 2cec25a..4404d21 100644 (file)
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -826,9 +826,12 @@ static const struct super_operations fuse_super_operations = {
 
 static void sanitize_global_limit(unsigned *limit)
 {
+       /*
+        * The default maximum number of async requests is calculated to consume
+        * 1/2^13 of the total memory, assuming 392 bytes per request.
+        */
        if (*limit == 0)
-               *limit = ((totalram_pages() << PAGE_SHIFT) >> 13) /
-                        sizeof(struct fuse_req);
+               *limit = ((totalram_pages() << PAGE_SHIFT) >> 13) / 392;
 
        if (*limit >= 1 << 16)
                *limit = (1 << 16) - 1;