tree:   https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git netfs-folio-regions
head:   2f3fe780e9a44691136170536363c701b527d0e8
commit: 7261c29990677f14498f0aa1749db277a581b9c3 [13/36] netfs: Add a netfs inode context
config: i386-randconfig-s031-20210830 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-348-gf0e6938b-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/commit/?id=7261c29990677f14498f0aa1749db277a581b9c3
        git remote add dhowells-fs https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
        git fetch --no-tags dhowells-fs netfs-folio-regions
        git checkout 7261c29990677f14498f0aa1749db277a581b9c3
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   fs/netfs/read_helper.c: In function 'netfs_write_begin':
>> fs/netfs/read_helper.c:1260:7: error: implicit declaration of function 'netfs_is_cache_enabled' [-Werror=implicit-function-declaration]
    1260 |  if (!netfs_is_cache_enabled(ctx) &&
         |       ^~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/netfs_is_cache_enabled +1260 fs/netfs/read_helper.c

  1187	
  1188	/**
  1189	 * netfs_write_begin - Helper to prepare for writing
  1190	 * @file: The file to read from
  1191	 * @mapping: The mapping to read from
  1192	 * @pos: File position at which the write will begin
  1193	 * @len: The length of the write (may extend beyond the end of the folio chosen)
  1194	 * @aop_flags: AOP_* flags
  1195	 * @_folio: Where to put the resultant folio
  1196	 * @_fsdata: Place for the netfs to store a cookie
  1197	 *
  1198	 * Pre-read data for a write-begin request by drawing data from the cache if
  1199	 * possible, or the netfs if not.  Space beyond the EOF is zero-filled.
  1200	 * Multiple I/O requests from different sources will get munged together.  If
  1201	 * necessary, the readahead window can be expanded in either direction to a
  1202	 * more convenient alighment for RPC efficiency or to make storage in the cache
  1203	 * feasible.
  1204	 *
  1205	 * The calling netfs must provide a table of operations, only one of which,
  1206	 * issue_op, is mandatory.
  1207	 *
  1208	 * The check_write_begin() operation can be provided to check for and flush
  1209	 * conflicting writes once the folio is grabbed and locked.  It is passed a
  1210	 * pointer to the fsdata cookie that gets returned to the VM to be passed to
  1211	 * write_end.  It is permitted to sleep.  It should return 0 if the request
  1212	 * should go ahead; unlock the folio and return -EAGAIN to cause the folio to
  1213	 * be regot; or return an error.
  1214	 *
  1215	 * The calling netfs must initialise a netfs context contiguous to the vfs
  1216	 * inode before calling this.
  1217	 *
  1218	 * This is usable whether or not caching is enabled.
  1219	 */
  1220	int netfs_write_begin(struct file *file, struct address_space *mapping,
  1221			      loff_t pos, unsigned int len, unsigned int aop_flags,
  1222			      struct folio **_folio, void **_fsdata)
  1223	{
  1224		struct netfs_read_request *rreq;
  1225		struct netfs_i_context *ctx = netfs_i_context(file_inode(file ));
  1226		struct folio *folio;
  1227		unsigned int debug_index = 0, fgp_flags;
  1228		pgoff_t index = pos >> PAGE_SHIFT;
  1229		int ret;
  1230	
  1231		DEFINE_READAHEAD(ractl, file, NULL, mapping, index);
  1232	
  1233	retry:
  1234		fgp_flags = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE;
  1235		if (aop_flags & AOP_FLAG_NOFS)
  1236			fgp_flags |= FGP_NOFS;
  1237		folio = __filemap_get_folio(mapping, index, fgp_flags,
  1238					    mapping_gfp_mask(mapping));
  1239		if (!folio)
  1240			return -ENOMEM;
  1241	
  1242		if (ctx->ops->check_write_begin) {
  1243			/* Allow the netfs (eg. ceph) to flush conflicts. */
  1244			ret = ctx->ops->check_write_begin(file, pos, len, folio, _fsdata);
  1245			if (ret < 0) {
  1246				trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);
  1247				if (ret == -EAGAIN)
  1248					goto retry;
  1249				goto error;
  1250			}
  1251		}
  1252	
  1253		if (folio_test_uptodate(folio))
  1254			goto have_folio;
  1255	
  1256		/* If the folio is beyond the EOF, we want to clear it - unless it's
  1257		 * within the cache granule containing the EOF, in which case we need
  1258		 * to preload the granule.
  1259		 */
> 1260		if (!netfs_is_cache_enabled(ctx) &&

---
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