LINUX: fix RedHat 7.5 ENOTDIR issues

Red Hat Linux 7.5 beta introduces a new file->f_mode flag
FMODE_KABI_ITERATE as a means for certain in-tree filesystems to
indicate that they have implemented file operation iterate() instead of
readdir().  The kernel routine iterate_dir() tests this flag to decide
whether to invoke the file operation iterate() or readdir().

The OpenAFS configure script detects that the file operation iterate()
is available under RH7.5 and so implements iterate() as
afs_linux_readdir().  However, since OpenAFS does not set
FMODE_KABI_ITERATE on any of its files, the kernel's iterate_dir() will
not invoke iterate() for any OpenAFS files.  OpenAFS has also not
implemented readdir(), so iterate_dir() must return -ENOTDIR.

Instead, modify OpenAFS to fall back to readdir() in this case.

Reviewed-on: https://gerrit.openafs.org/12935
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit c818f86b79a636532d396887d4f22cc196c86288)

Change-Id: I71386b17f0c751b69c86ef0f5766a5baf3dc36bd
Reviewed-on: https://gerrit.openafs.org/12950
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>

diff --git a/src/afs/LINUX/osi_vnodeops.c b/src/afs/LINUX/osi_vnodeops.c
index c1acca962337dff1cf66916c1e3e876bd8468e54..969a27b271ed3b809f1ddaa462099a5cc09d7886 100644 (file)
--- a/src/afs/LINUX/osi_vnodeops.c
+++ b/src/afs/LINUX/osi_vnodeops.c
@@ -53,6 +53,16 @@
 # define D_SPLICE_ALIAS_RACE
 #endif
 
+/* Workaround for RH 7.5 which introduced file operation iterate() but requires
+ * each file->f_mode to be marked with FMODE_KABI_ITERATE.  Instead OpenAFS will
+ * continue to use file opearation readdir() in this case.
+ */
+#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE) && !defined(FMODE_KABI_ITERATE)
+#define USE_FOP_ITERATE 1
+#else
+#undef USE_FOP_ITERATE
+#endif
+
 int cachefs_noreadpage = 0;
 
 extern struct backing_dev_info *afs_backing_dev_info;
@@ -302,7 +312,7 @@ extern int BlobScan(struct dcache * afile, afs_int32 ablob, afs_int32 *ablobOut)
  * handling and use of bulkstats will need to be reflected here as well.
  */
 static int
-#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE)
+#if defined(USE_FOP_ITERATE)
 afs_linux_readdir(struct file *fp, struct dir_context *ctx)
 #else
 afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
@@ -385,7 +395,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
      * takes an offset in units of blobs, rather than bytes.
      */
     code = 0;
-#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE)
+#if defined(USE_FOP_ITERATE)
     offset = ctx->pos;
 #else
     offset = (int) fp->f_pos;
@@ -455,7 +465,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
             * holding the GLOCK.
             */
            AFS_GUNLOCK();
-#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE)
+#if defined(USE_FOP_ITERATE)
            /* dir_emit returns a bool - true when it succeeds.
             * Inverse the result to fit with how we check "code" */
            code = !dir_emit(ctx, de->name, len, ino, type);
@@ -475,7 +485,7 @@ afs_linux_readdir(struct file *fp, void *dirbuf, filldir_t filldir)
     code = 0;
 
 unlock_out:
-#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE)
+#if defined(USE_FOP_ITERATE)
     ctx->pos = (loff_t) offset;
 #else
     fp->f_pos = (loff_t) offset;
@@ -798,7 +808,7 @@ out:
 
 struct file_operations afs_dir_fops = {
   .read =      generic_read_dir,
-#if defined(STRUCT_FILE_OPERATIONS_HAS_ITERATE)
+#if defined(USE_FOP_ITERATE)
   .iterate =   afs_linux_readdir,
 #else
   .readdir =   afs_linux_readdir,