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ocfs2: Make cached block reads the common case.

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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>
This commit is contained in:
Joel Becker
2008-10-09 17:20:34 -07:00
committed by Mark Fasheh
parent 5e0b3dec01
commit d4a8c93c82
7 changed files with 24 additions and 17 deletions
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19
fs/ocfs2/buffer_head_io.c
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@@ -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: