Messages in this thread Patch in this message | | | Subject | Re: [PATCH] jfs: clear PAGECACHE_TAG_DIRTY for no-write pages | From | Dave Kleikamp <> | Date | Fri, 28 Dec 2007 10:53:14 -0600 |
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On Fri, 2007-12-28 at 10:25 -0600, Dave Kleikamp wrote: > On Fri, 2007-12-28 at 12:33 +0100, Peter Zijlstra wrote:
> > I'm not liking this open-coded tag_clear, although I currently fail to > > come up with a nice solution. > > I'm looking at __block_write_full_page() for guidance. The situation > here is similar to writing a page where all the bufferheads are clean. > __block_write_full_page() always calls set_page_writeback(page), and > then, if no I/O is initiated, immediately calls > end_page_writeback(page). > > I'll put together a patch for testing.
Here it is, compile-test only so far. I borrowed some of the changeset comments from Fengguang.
JFS: clear PAGECACHE_TAG_DIRTY for no-write pages
When JFS decides to drop a dirty metapage, it simply clears the META_dirty bit and leave alone the PG_dirty and PAGECACHE_TAG_DIRTY bits.
When such no-write page goes to metapage_writepage(), the `relic' PAGECACHE_TAG_DIRTY tag should be cleared, to prevent pdflush from repeatedly trying to sync them. This is done through set_page_writeback(), so call it should be called in all cases. If no I/O is initiated, end_page_writeback() should be called immediately.
This is how __block_write_full_page() does things.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com> CC: Fengguang Wu <wfg@mail.ustc.edu.cn> ---
diff -Nurp linux-2.6.24-rc6-git5/fs/jfs/jfs_metapage.c linux/fs/jfs/jfs_metapage.c --- linux-2.6.24-rc6-git5/fs/jfs/jfs_metapage.c 2007-12-28 10:28:33.000000000 -0600 +++ linux/fs/jfs/jfs_metapage.c 2007-12-28 10:37:30.000000000 -0600 @@ -360,6 +360,7 @@ static int metapage_writepage(struct pag struct metapage *mp; int redirty = 0; sector_t lblock; + int nr_underway = 0; sector_t pblock; sector_t next_block = 0; sector_t page_start; @@ -371,6 +372,7 @@ static int metapage_writepage(struct pag (PAGE_CACHE_SHIFT - inode->i_blkbits); BUG_ON(!PageLocked(page)); BUG_ON(PageWriteback(page)); + set_page_writeback(page); for (offset = 0; offset < PAGE_CACHE_SIZE; offset += PSIZE) { mp = page_to_mp(page, offset); @@ -413,11 +415,10 @@ static int metapage_writepage(struct pag if (!bio->bi_size) goto dump_bio; submit_bio(WRITE, bio); + nr_underway++; bio = NULL; - } else { - set_page_writeback(page); + } else inc_io(page); - } xlen = (PAGE_CACHE_SIZE - offset) >> inode->i_blkbits; pblock = metapage_get_blocks(inode, lblock, &xlen); if (!pblock) { @@ -449,12 +450,16 @@ static int metapage_writepage(struct pag goto dump_bio; submit_bio(WRITE, bio); + nr_underway++; } if (redirty) redirty_page_for_writepage(wbc, page); unlock_page(page); + if (nr_underway == 0) + end_page_writeback(page); + return 0; add_failed: /* We should never reach here, since we're only adding one vec */ -- David Kleikamp IBM Linux Technology Center
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