Re: [PATCH V5 15/19] famfs_fuse: Plumb dax iomap and fuse read/write/mmap

[kernel test robot <lkp@intel.com>]

Hi John,

kernel test robot noticed the following build warnings:

[auto build test WARNING on mszeredi-fuse/for-next]
[also build test WARNING on brauner-vfs/vfs.all v6.19-rc5]
[cannot apply to linus/master next-20260116]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/John-Groves/dax-Factor-out-dax_folio_reset_order-helper/20260117-031401
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git for-next
patch link:    https://lore.kernel.org/r/0100019bc834ead9-7ed67793-5e18-45f6-80cc-146cfd7d4c8a-000000%40email.amazonses.com
patch subject: [PATCH V5 15/19] famfs_fuse: Plumb dax iomap and fuse read/write/mmap
config: s390-defconfig (https://download.01.org/0day-ci/archive/20260117/202601170925.1qbFpAwE-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260117/202601170925.1qbFpAwE-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601170925.1qbFpAwE-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> fs/fuse/famfs.c:610:22: warning: variable 'ext_size' is uninitialized when used within its own initialization [-Wuninitialized]
     610 |                 u64 ext_size = min(ext_size, meta->file_size);
         |                     ~~~~~~~~       ^~~~~~~~
   include/linux/minmax.h:105:38: note: expanded from macro 'min'
     105 | #define min(x, y)       __careful_cmp(min, x, y)
         |                                            ^
   include/linux/minmax.h:98:25: note: expanded from macro '__careful_cmp'
      98 |         __careful_cmp_once(op, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
         |                                ^
   include/linux/minmax.h:92:13: note: expanded from macro '__careful_cmp_once'
      92 |         auto ux = (x); auto uy = (y);                   \
         |                    ^
   1 warning generated.


vim +/ext_size +610 fs/fuse/famfs.c

   585	
   586	static int
   587	famfs_interleave_fileofs_to_daxofs(struct inode *inode, struct iomap *iomap,
   588				 loff_t file_offset, off_t len, unsigned int flags)
   589	{
   590		struct fuse_inode *fi = get_fuse_inode(inode);
   591		struct famfs_file_meta *meta = fi->famfs_meta;
   592		struct fuse_conn *fc = get_fuse_conn(inode);
   593		loff_t local_offset = file_offset;
   594	
   595		/* This function is only for extent_type INTERLEAVED_EXTENT */
   596		if (meta->fm_extent_type != INTERLEAVED_EXTENT) {
   597			pr_err("%s: bad extent type\n", __func__);
   598			goto err_out;
   599		}
   600	
   601		if (famfs_file_bad(inode))
   602			goto err_out;
   603	
   604		iomap->offset = file_offset;
   605	
   606		for (int i = 0; i < meta->fm_niext; i++) {
   607			struct famfs_meta_interleaved_ext *fei = &meta->ie[i];
   608			u64 chunk_size = fei->fie_chunk_size;
   609			u64 nstrips = fei->fie_nstrips;
 > 610			u64 ext_size = min(ext_size, meta->file_size);
   611	
   612			if (ext_size == 0) {
   613				pr_err("%s: ext_size=%lld file_size=%ld\n",
   614				       __func__, fei->fie_nbytes, meta->file_size);
   615				goto err_out;
   616			}
   617	
   618			/* Is the data is in this striped extent? */
   619			if (local_offset < ext_size) {
   620				u64 chunk_num       = local_offset / chunk_size;
   621				u64 chunk_offset    = local_offset % chunk_size;
   622				u64 chunk_remainder = chunk_size - chunk_offset;
   623				u64 stripe_num      = chunk_num / nstrips;
   624				u64 strip_num       = chunk_num % nstrips;
   625				u64 strip_offset    = chunk_offset + (stripe_num * chunk_size);
   626				u64 strip_dax_ofs = fei->ie_strips[strip_num].ext_offset;
   627				u64 strip_devidx = fei->ie_strips[strip_num].dev_index;
   628	
   629				if (strip_devidx >= fc->dax_devlist->nslots) {
   630					pr_err("%s: strip_devidx %llu >= nslots %d\n",
   631					       __func__, strip_devidx,
   632					       fc->dax_devlist->nslots);
   633					goto err_out;
   634				}
   635	
   636				if (!fc->dax_devlist->devlist[strip_devidx].valid) {
   637					pr_err("%s: daxdev=%lld invalid\n", __func__,
   638						strip_devidx);
   639					goto err_out;
   640				}
   641	
   642				iomap->addr    = strip_dax_ofs + strip_offset;
   643				iomap->offset  = file_offset;
   644				iomap->length  = min_t(loff_t, len, chunk_remainder);
   645	
   646				iomap->dax_dev = fc->dax_devlist->devlist[strip_devidx].devp;
   647	
   648				iomap->type    = IOMAP_MAPPED;
   649				iomap->flags   = flags;
   650	
   651				return 0;
   652			}
   653			local_offset -= ext_size; /* offset is beyond this striped extent */
   654		}
   655	
   656	 err_out:
   657		pr_err("%s: err_out\n", __func__);
   658	
   659		/* We fell out the end of the extent list.
   660		 * Set iomap to zero length in this case, and return 0
   661		 * This just means that the r/w is past EOF
   662		 */
   663		iomap->addr    = 0; /* there is no valid dax device offset */
   664		iomap->offset  = file_offset; /* file offset */
   665		iomap->length  = 0; /* this had better result in no access to dax mem */
   666		iomap->dax_dev = NULL;
   667		iomap->type    = IOMAP_MAPPED;
   668		iomap->flags   = flags;
   669	
   670		return -EIO;
   671	}
   672	

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