coda: add hinting support for partial file caching

This adds support for partial file caching in Coda.  Every read, write
and mmap informs the userspace cache manager about what part of a file
is about to be accessed so that the cache manager can ensure the
relevant parts are available before the operation is allowed to proceed.

When a read or write operation completes, this is also reported to allow
the cache manager to track when partially cached content can be
released.

If the cache manager does not support partial file caching, or when the
entire file has been fetched into the local cache, the cache manager may
return an EOPNOTSUPP error to indicate that intent upcalls are no longer
necessary until the file is closed.

[akpm@linux-foundation.org: little whitespace fixup]
Link: http://lkml.kernel.org/r/20190618181301.6960-1-jaharkes@cs.cmu.edu
Signed-off-by: Pedro Cuadra <pjcuadra@gmail.com>
Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 27 insertions, 2 deletions

diff --git a/include/uapi/linux/coda.h b/include/uapi/linux/coda.h
index 5dba636b6e11..aa34c2dcae8d 100644
--- a/include/uapi/linux/coda.h
+++ b/include/uapi/linux/coda.h
@@ -271,7 +271,8 @@ struct coda_statfs {
 #define CODA_STATFS      34
 #define CODA_STORE       35
 #define CODA_RELEASE     36
-#define CODA_NCALLS 37
+#define CODA_ACCESS_INTENT 37
+#define CODA_NCALLS 38
 
 #define DOWNCALL(opcode) (opcode >= CODA_REPLACE && opcode <= CODA_PURGEFID)
 
@@ -281,8 +282,12 @@ struct coda_statfs {
 
 #define CIOC_KERNEL_VERSION _IOWR('c', 10, size_t)
 
+//      CODA_KERNEL_VERSION 0 /* don't care about kernel version number */
+//      CODA_KERNEL_VERSION 1 /* The old venus 4.6 compatible interface */
+//      CODA_KERNEL_VERSION 2 /* venus_lookup gets an extra parameter */
 //      CODA_KERNEL_VERSION 3 /* 128-bit file identifiers */
-#define CODA_KERNEL_VERSION 4 /* 64-bit timespec */
+//      CODA_KERNEL_VERSION 4 /* 64-bit timespec */
+#define CODA_KERNEL_VERSION 5 /* access intent support */
 
 /*
  *        Venus <-> Coda  RPC arguments
@@ -637,6 +642,25 @@ struct coda_statfs_out {
     struct coda_statfs stat;
 };
 
+#define CODA_ACCESS_TYPE_READ           1
+#define CODA_ACCESS_TYPE_WRITE          2
+#define CODA_ACCESS_TYPE_MMAP           3
+#define CODA_ACCESS_TYPE_READ_FINISH    4
+#define CODA_ACCESS_TYPE_WRITE_FINISH   5
+
+/* coda_access_intent: NO_OUT */
+struct coda_access_intent_in {
+        struct coda_in_hdr ih;
+        struct CodaFid VFid;
+        int count;
+        int pos;
+        int type;
+};
+
+struct coda_access_intent_out {
+        struct coda_out_hdr out;
+};
+
 /* 
  * Occasionally, we don't cache the fid returned by CODA_LOOKUP. 
  * For instance, if the fid is inconsistent. 
@@ -668,6 +692,7 @@ union inputArgs {
     struct coda_open_by_fd_in coda_open_by_fd;
     struct coda_open_by_path_in coda_open_by_path;
     struct coda_statfs_in coda_statfs;
+    struct coda_access_intent_in coda_access_intent;
 };
 
 union outputArgs {