Re: [RESEND4, PATCH 1/2] fuse: retrieve: cap requested size to negotiated max_write

On Wed, Apr 24, 2019 at 4:22 PM Kirill Smelkov kirr@nexedi.com wrote:

• FUSE_PRECISE_INVAL_DATA:

  --- b/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -266,7 +266,7 @@ * FUSE_MAX_PAGES: init_out.max_pages contains the max number of req pages * FUSE_CACHE_SYMLINKS: cache READLINK responses * FUSE_NO_OPENDIR_SUPPORT: kernel supports zero-message opendir

  • • FUSE_PRECISE_INVAL_DATA: filesystem is fully responsible for data cache invalidation
  • • FUSE_PRECISE_INVAL_DATA: filesystem is fully responsible for invalidation
    */

  #define FUSE_ASYNC_READ (1 << 0) #define FUSE_POSIX_LOCKS (1 << 1)

the "data cache" in "for data cache invalidation" has particular meaning and semantic: the filesystem promises to explicitly invalidate data of

Right; better name: FUSE_EXPLICIT_INVAL_DATA. Will push fixed version.

Your amendment for FOPEN_STREAM in uapi/linux/fuse.h (see above) also suggests that it is better to be more explicit in that file.

--- b/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -913,13 +913,8 @@
                                fc->dont_mask = 1;
                        if (arg->flags & FUSE_AUTO_INVAL_DATA)
                                fc->auto_inval_data = 1;
-                       if (arg->flags & FUSE_PRECISE_INVAL_DATA)
+                       else if (arg->flags & FUSE_PRECISE_INVAL_DATA)
                                fc->precise_inval_data = 1;
-                       if (fc->auto_inval_data && fc->precise_inval_data) {
-                               pr_warn("filesystem requested both auto and "
-                                       "precise cache control - using auto\n");
-                               fc->precise_inval_data = 0;
-                       }
                        if (arg->flags & FUSE_DO_READDIRPLUS) {
                                fc->do_readdirplus = 1;
                                if (arg->flags & FUSE_READDIRPLUS_AUTO)

Even though it is ok for me personally (I could be careful and use only FUSE_PRECISE_INVAL_DATA) I still think usage of both "auto" and "precise" invalidation modes deserves a warning. It is only at filesystem init time. What is the reason not to print it?

The warning makes no sense. It should either be failure or silent override.

• "fuse: retrieve: cap requested size to negotiated max_write"

  Signed-off-by: Kirill Smelkov kirr@nexedi.com Cc: Han-Wen Nienhuys hanwen@google.com Cc: Jakob Unterwurzacher jakobunt@gmail.com -Cc: stable@vger.kernel.org # v2.6.36+

what is the reason not to include this patch into stable series?

This doens't fix any bugs out there, but there is a slight chance of regression (so it might possibly have to be reverted in the future) so it absolutely makes no sense to backport it to stable.

Thanks, Miklos