ceph: perform lazy reads when file mode and caps permit

If the file mode is marked as "lazy," perform cached/buffered reads when
the caps permit it.  Adjust the rdcache_gen and invalidation logic
accordingly so that we manage our cache based on the FILE_CACHE -or-
FILE_LAZYIO cap bits.

Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/addr.c

@@ -552,7 +552,7 @@ static void writepages_finish(struct ceph_osd_request *req,
 		 * page truncation thread, possibly losing some data that
 		 * raced its way in
 		 */
-		if ((issued & CEPH_CAP_FILE_CACHE) == 0)
+		if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
 			generic_error_remove_page(inode->i_mapping, page);
 
 		unlock_page(page);

fs/ceph/caps.c

@@ -482,8 +482,8 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
 	 * Each time we receive FILE_CACHE anew, we increment
 	 * i_rdcache_gen.
 	 */
-	if ((issued & CEPH_CAP_FILE_CACHE) &&
-	    (had & CEPH_CAP_FILE_CACHE) == 0)
+	if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) &&
+	    (had & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0)
 		ci->i_rdcache_gen++;
 
 	/*
@@ -1509,11 +1509,13 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags,
 	    ci->i_wrbuffer_ref == 0 &&               /* no dirty pages... */
 	    ci->i_rdcache_gen &&                     /* may have cached pages */
 	    (file_wanted == 0 ||                     /* no open files */
-	     (revoking & CEPH_CAP_FILE_CACHE)) &&     /*  or revoking cache */
+	     (revoking & (CEPH_CAP_FILE_CACHE|
+			  CEPH_CAP_FILE_LAZYIO))) && /*  or revoking cache */
 	    !tried_invalidate) {
 		dout("check_caps trying to invalidate on %p\n", inode);
 		if (try_nonblocking_invalidate(inode) < 0) {
-			if (revoking & CEPH_CAP_FILE_CACHE) {
+			if (revoking & (CEPH_CAP_FILE_CACHE|
+					CEPH_CAP_FILE_LAZYIO)) {
 				dout("check_caps queuing invalidate\n");
 				queue_invalidate = 1;
 				ci->i_rdcache_revoking = ci->i_rdcache_gen;
@@ -2276,7 +2278,8 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 	 * try to invalidate (once).  (If there are dirty buffers, we
 	 * will invalidate _after_ writeback.)
 	 */
-	if (((cap->issued & ~newcaps) & CEPH_CAP_FILE_CACHE) &&
+	if (((cap->issued & ~newcaps) & (CEPH_CAP_FILE_CACHE|
+					 CEPH_CAP_FILE_LAZYIO)) &&
 	    !ci->i_wrbuffer_ref) {
 		if (try_nonblocking_invalidate(inode) == 0) {
 			revoked_rdcache = 1;
@@ -2374,7 +2377,8 @@ static void handle_cap_grant(struct inode *inode, struct ceph_mds_caps *grant,
 			writeback = 1; /* will delay ack */
 		else if (dirty & ~newcaps)
 			check_caps = 1;  /* initiate writeback in check_caps */
-		else if (((used & ~newcaps) & CEPH_CAP_FILE_CACHE) == 0 ||
+		else if (((used & ~newcaps) & (CEPH_CAP_FILE_CACHE|
+					       CEPH_CAP_FILE_LAZYIO)) == 0 ||
 			   revoked_rdcache)
 			check_caps = 2;     /* send revoke ack in check_caps */
 		cap->issued = newcaps;

fs/ceph/file.c

@@ -740,28 +740,32 @@ static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
 			     unsigned long nr_segs, loff_t pos)
 {
 	struct file *filp = iocb->ki_filp;
+	struct ceph_file_info *fi = filp->private_data;
 	loff_t *ppos = &iocb->ki_pos;
 	size_t len = iov->iov_len;
 	struct inode *inode = filp->f_dentry->d_inode;
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	void *base = iov->iov_base;
 	ssize_t ret;
-	int got = 0;
+	int want, got = 0;
 	int checkeof = 0, read = 0;
 
 	dout("aio_read %p %llx.%llx %llu~%u trying to get caps on %p\n",
 	     inode, ceph_vinop(inode), pos, (unsigned)len, inode);
 again:
 	__ceph_do_pending_vmtruncate(inode);
-	ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, CEPH_CAP_FILE_CACHE,
-			    &got, -1);
+	if (fi->fmode & CEPH_FILE_MODE_LAZY)
+		want = CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO;
+	else
+		want = CEPH_CAP_FILE_CACHE;
+	ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, want, &got, -1);
 	if (ret < 0)
 		goto out;
 	dout("aio_read %p %llx.%llx %llu~%u got cap refs on %s\n",
 	     inode, ceph_vinop(inode), pos, (unsigned)len,
 	     ceph_cap_string(got));
 
-	if ((got & CEPH_CAP_FILE_CACHE) == 0 ||
+	if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
 	    (iocb->ki_filp->f_flags & O_DIRECT) ||
 	    (inode->i_sb->s_flags & MS_SYNCHRONOUS))
 		/* hmm, this isn't really async... */

fs/ceph/inode.c

@@ -442,8 +442,9 @@ int ceph_fill_file_size(struct inode *inode, int issued,
 			 * the file is either opened or mmaped
 			 */
 			if ((issued & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_RD|
-				      CEPH_CAP_FILE_WR|CEPH_CAP_FILE_BUFFER|
-				      CEPH_CAP_FILE_EXCL)) ||
+				       CEPH_CAP_FILE_WR|CEPH_CAP_FILE_BUFFER|
+				       CEPH_CAP_FILE_EXCL|
+				       CEPH_CAP_FILE_LAZYIO)) ||
 			    mapping_mapped(inode->i_mapping) ||
 			    __ceph_caps_file_wanted(ci)) {
 				ci->i_truncate_pending++;