ocfs2: Make cached block reads the common case.

ocfs2_read_blocks() currently requires the CACHED flag for cached I/O.
However, that's the common case.  Let's flip it around and provide an
IGNORE_CACHE flag for the special users.  This has the added benefit of
cleaning up the code some (ignore_cache takes on its special meaning
earlier in the loop).

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c
index 718dbe5607ca..7e947c672469 100644
--- a/fs/ocfs2/buffer_head_io.c
+++ b/fs/ocfs2/buffer_head_io.c
@@ -181,7 +181,8 @@ int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
                    inode, (unsigned long long)block, nr, flags);
 
         BUG_ON(!inode);
-        BUG_ON((flags & OCFS2_BH_READAHEAD) && !(flags & OCFS2_BH_CACHED));
+        BUG_ON((flags & OCFS2_BH_READAHEAD) &&
+               (flags & OCFS2_BH_IGNORE_CACHE));
 
         if (bhs == NULL) {
                 status = -EINVAL;
@@ -214,7 +215,7 @@ int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
                         }
                 }
                 bh = bhs[i];
-                ignore_cache = 0;
+                ignore_cache = (flags & OCFS2_BH_IGNORE_CACHE);
 
                 /* There are three read-ahead cases here which we need to
                  * be concerned with. All three assume a buffer has
@@ -240,26 +241,27 @@ int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
                  *    before our is-it-in-flight check.
                  */
 
-                if (flags & OCFS2_BH_CACHED &&
-                    !ocfs2_buffer_uptodate(inode, bh)) {
+                if (!ignore_cache && !ocfs2_buffer_uptodate(inode, bh)) {
                         mlog(ML_UPTODATE,
                              "bh (%llu), inode %llu not uptodate\n",
                              (unsigned long long)bh->b_blocknr,
                              (unsigned long long)OCFS2_I(inode)->ip_blkno);
+                        /* We're using ignore_cache here to say
+                         * "go to disk" */
                         ignore_cache = 1;
                 }
 
                 /* XXX: Can we ever get this and *not* have the cached
                  * flag set? */
                 if (buffer_jbd(bh)) {
-                        if (!(flags & OCFS2_BH_CACHED) || ignore_cache)
+                        if (ignore_cache)
                                 mlog(ML_BH_IO, "trying to sync read a jbd "
                                                "managed bh (blocknr = %llu)\n",
                                      (unsigned long long)bh->b_blocknr);
                         continue;
                 }
 
-                if (!(flags & OCFS2_BH_CACHED) || ignore_cache) {
+                if (ignore_cache) {
                         if (buffer_dirty(bh)) {
                                 /* This should probably be a BUG, or
                                  * at least return an error. */
@@ -294,7 +296,7 @@ int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
                          * previously read-ahead buffer may have
                          * completed I/O while we were waiting for the
                          * buffer lock. */
-                        if ((flags & OCFS2_BH_CACHED)
+                        if (!(flags & OCFS2_BH_IGNORE_CACHE)
                             && !(flags & OCFS2_BH_READAHEAD)
                             && ocfs2_buffer_uptodate(inode, bh)) {
                                 unlock_buffer(bh);
@@ -344,7 +346,8 @@ int ocfs2_read_blocks(struct inode *inode, u64 block, int nr,
 
         mlog(ML_BH_IO, "block=(%llu), nr=(%d), cached=%s, flags=0x%x\n", 
              (unsigned long long)block, nr,
-             (!(flags & OCFS2_BH_CACHED) || ignore_cache) ? "no" : "yes", flags);
+             ((flags & OCFS2_BH_IGNORE_CACHE) || ignore_cache) ? "no" : "yes",
+             flags);
 
 bail: