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Old 01-21-2008, 08:21 AM
 
Default Split gfs2_writepage into three cases

From: Steven Whitehouse <swhiteho@redhat.com>

This patch splits gfs2_writepage into separate functions for each of
the three cases: writeback, ordered and journalled. As a result
it becomes a lot easier to see what each one is doing. The common
code is moved into gfs2_writepage_common.

This fixes a performance bug where we were doing more work than
strictly required in the ordered write case.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 6c27cea..e901f8f 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -556,17 +556,20 @@ static void databuf_lo_add(struct gfs2_sbd *sdp, struct gfs2_log_element *le)

lock_buffer(bd->bd_bh);
gfs2_log_lock(sdp);
- if (!list_empty(&bd->bd_list_tr))
- goto out;
- tr->tr_touched = 1;
- if (gfs2_is_jdata(ip)) {
- tr->tr_num_buf++;
- list_add(&bd->bd_list_tr, &tr->tr_list_buf);
+ if (tr) {
+ if (!list_empty(&bd->bd_list_tr))
+ goto out;
+ tr->tr_touched = 1;
+ if (gfs2_is_jdata(ip)) {
+ tr->tr_num_buf++;
+ list_add(&bd->bd_list_tr, &tr->tr_list_buf);
+ }
}
if (!list_empty(&le->le_list))
goto out;

- __glock_lo_add(sdp, &bd->bd_gl->gl_le);
+ if (tr)
+ __glock_lo_add(sdp, &bd->bd_gl->gl_le);
if (gfs2_is_jdata(ip)) {
gfs2_pin(sdp, bd->bd_bh);
tr->tr_num_databuf_new++;
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index 207014f..4bf73ed 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -103,16 +103,15 @@ static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
}

/**
- * gfs2_writepage - Write complete page
- * @page: Page to write
- *
- * Returns: errno
+ * gfs2_writepage_common - Common bits of writepage
+ * @page: The page to be written
+ * @wbc: The writeback control
*
- * Some of this is copied from block_write_full_page() although we still
- * call it to do most of the work.
+ * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
*/

-static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
+static int gfs2_writepage_common(struct page *page,
+ struct writeback_control *wbc)
{
struct inode *inode = page->mapping->host;
struct gfs2_inode *ip = GFS2_I(inode);
@@ -120,23 +119,94 @@ static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
loff_t i_size = i_size_read(inode);
pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
- int error;
- int done_trans = 0;
+ int ret = -EIO;

- if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
- unlock_page(page);
- return -EIO;
- }
+ if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
+ goto out;
+ ret = 0;
if (current->journal_info)
- goto out_ignore;
-
+ goto redirty;
/* Is the page fully outside i_size? (truncate in progress) */
- offset = i_size & (PAGE_CACHE_SIZE-1);
+ offset = i_size & (PAGE_CACHE_SIZE-1);
if (page->index > end_index || (page->index == end_index && !offset)) {
page->mapping->a_ops->invalidatepage(page, 0);
- unlock_page(page);
- return 0; /* don't care */
+ goto out;
}
+ return 1;
+redirty:
+ redirty_page_for_writepage(wbc, page);
+out:
+ unlock_page(page);
+ return 0;
+}
+
+/**
+ * gfs2_writeback_writepage - Write page for writeback mappings
+ * @page: The page
+ * @wbc: The writeback control
+ *
+ */
+
+static int gfs2_writeback_writepage(struct page *page,
+ struct writeback_control *wbc)
+{
+ int ret;
+
+ ret = gfs2_writepage_common(page, wbc);
+ if (ret <= 0)
+ return ret;
+
+ ret = mpage_writepage(page, gfs2_get_block_noalloc, wbc);
+ if (ret == -EAGAIN)
+ ret = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
+ return ret;
+}
+
+/**
+ * gfs2_ordered_writepage - Write page for ordered data files
+ * @page: The page to write
+ * @wbc: The writeback control
+ *
+ */
+
+static int gfs2_ordered_writepage(struct page *page,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ struct gfs2_inode *ip = GFS2_I(inode);
+ int ret;
+
+ ret = gfs2_writepage_common(page, wbc);
+ if (ret <= 0)
+ return ret;
+
+ if (!page_has_buffers(page)) {
+ create_empty_buffers(page, inode->i_sb->s_blocksize,
+ (1 << BH_Dirty)|(1 << BH_Uptodate));
+ }
+ gfs2_page_add_databufs(ip, page, 0, inode->i_sb->s_blocksize-1);
+ return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
+}
+
+/**
+ * gfs2_jdata_writepage - Write complete page
+ * @page: Page to write
+ *
+ * Returns: errno
+ *
+ */
+
+static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ struct gfs2_inode *ip = GFS2_I(inode);
+ struct gfs2_sbd *sdp = GFS2_SB(inode);
+ int error;
+ int done_trans = 0;
+
+ error = gfs2_writepage_common(page, wbc);
+ if (error <= 0)
+ return error;

if (PageChecked(page)) {
error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
@@ -838,7 +908,7 @@ cannot_release:
}

static const struct address_space_operations gfs2_writeback_aops = {
- .writepage = gfs2_writepage,
+ .writepage = gfs2_writeback_writepage,
.writepages = gfs2_writeback_writepages,
.readpage = gfs2_readpage,
.readpages = gfs2_readpages,
@@ -852,7 +922,7 @@ static const struct address_space_operations gfs2_writeback_aops = {
};

static const struct address_space_operations gfs2_ordered_aops = {
- .writepage = gfs2_writepage,
+ .writepage = gfs2_ordered_writepage,
.readpage = gfs2_readpage,
.readpages = gfs2_readpages,
.sync_page = block_sync_page,
@@ -866,7 +936,7 @@ static const struct address_space_operations gfs2_ordered_aops = {
};

static const struct address_space_operations gfs2_jdata_aops = {
- .writepage = gfs2_writepage,
+ .writepage = gfs2_jdata_writepage,
.readpage = gfs2_readpage,
.readpages = gfs2_readpages,
.sync_page = block_sync_page,
--
1.5.1.2
 

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