Convert wbc.range_cyclic to new behavior: when past EOF, abort writeback
of the inode, which instructs writeback_single_inode() to delay it for
a while if necessary.
It removes one inefficient .range_cyclic IO pattern when writeback_index
wraps:
submit [10000-10100], (wrap), submit [0-100]
In which the submitted pages may be consisted of two distant ranges.
It also prevents submitting pointless IO for busy overwriters.
CC: Steve French <sfrench@xxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/cifs/file.c | 18 ++++--------------
1 file changed, 4 insertions(+), 14 deletions(-)
--- linux.orig/fs/cifs/file.c 2009-10-06 23:37:49.000000000 +0800
+++ linux/fs/cifs/file.c 2009-10-06 23:38:33.000000000 +0800
@@ -1337,7 +1337,6 @@ static int cifs_partialpagewrite(struct
static int cifs_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
- struct backing_dev_info *bdi = mapping->backing_dev_info;
unsigned int bytes_to_write;
unsigned int bytes_written;
struct cifs_sb_info *cifs_sb;
@@ -1349,14 +1348,13 @@ static int cifs_writepages(struct addres
int len;
int n_iov = 0;
pgoff_t next;
- int nr_pages;
+ int nr_pages = 1;
__u64 offset = 0;
struct cifsFileInfo *open_file;
struct cifsInodeInfo *cifsi = CIFS_I(mapping->host);
struct page *page;
struct pagevec pvec;
int rc = 0;
- int scanned = 0;
int xid, long_op;
cifs_sb = CIFS_SB(mapping->host->i_sb);
@@ -1390,9 +1388,8 @@ static int cifs_writepages(struct addres
end = wbc->range_end >> PAGE_CACHE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
- scanned = 1;
}
-retry:
+
while (!done && (index <= end) &&
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
PAGECACHE_TAG_DIRTY,
@@ -1425,7 +1422,7 @@ retry:
break;
}
- if (!wbc->range_cyclic && page->index > end) {
+ if (page->index > end) {
done = 1;
unlock_page(page);
break;
@@ -1537,15 +1534,8 @@ retry:
pagevec_release(&pvec);
}
- if (!scanned && !done) {
- /*
- * We hit the last page and there is more work to be done: wrap
- * back to the start of the file
- */
- scanned = 1;
+ if (!nr_pages)
index = 0;
- goto retry;
- }
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
mapping->writeback_index = index;
--
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