Messages in this thread Patch in this message | | | Date | Sun, 1 Aug 2004 13:17:51 +0530 | From | Suparna Bhattacharya <> | Subject | Re: [PATCH 1/5] Writeback page range hint |
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On Sun, Aug 01, 2004 at 01:15:18PM +0530, Suparna Bhattacharya wrote: > > The attached patches (generated against 2.6.8-rc2) enable concurrent > O_SYNC writers to different parts of the same file by avoiding > serialising on i_sem across the wait for IO completion. > > This is mostly your work, ported to the tagged radix tree VFS changes > and a few fixes. I have been carrying these patches for sometime now; > they can be the merged upstream. Please apply. >
[1] writepages-range.patch
Regards Suparna
-- Suparna Bhattacharya (suparna@in.ibm.com) Linux Technology Center IBM Software Lab, India
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From: Andrew Morton <akpm@osdl.org>
Modify mpage_writepages to optionally only write back dirty pages within a specified range in a file (as in the case of O_SYNC). Cheat a little to avoid changes to prototypes of aops - just put the <start, end> hint into the writeback_control struct instead. If <start, end> are not set, then default to writing back all the mapping's dirty pages.
Signed-off-by: Suparna Bhattacharya <suparna@in.ibm.com>
linux-2.6.8-rc2-suparna/fs/mpage.c | 27 +++++++++++++++++++--- linux-2.6.8-rc2-suparna/include/linux/writeback.h | 21 +++++++++++++---- 2 files changed, 40 insertions(+), 8 deletions(-)
diff -puN fs/mpage.c~writepages-range fs/mpage.c --- linux-2.6.8-rc2/fs/mpage.c~writepages-range 2004-08-01 12:30:15.000000000 +0530 +++ linux-2.6.8-rc2-suparna/fs/mpage.c 2004-08-01 12:30:15.000000000 +0530 @@ -622,7 +622,9 @@ mpage_writepages(struct address_space *m struct pagevec pvec; int nr_pages; pgoff_t index; + pgoff_t end = -1; /* Inclusive */ int scanned = 0; + int is_range = 0; if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; @@ -640,9 +642,16 @@ mpage_writepages(struct address_space *m index = 0; /* whole-file sweep */ scanned = 1; } + if (wbc->start || wbc->end) { + index = wbc->start >> PAGE_CACHE_SHIFT; + end = wbc->end >> PAGE_CACHE_SHIFT; + is_range = 1; + scanned = 1; + } retry: while (!done && (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, - PAGECACHE_TAG_DIRTY, PAGEVEC_SIZE))) { + PAGECACHE_TAG_DIRTY, + min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) { unsigned i; scanned = 1; @@ -659,10 +668,21 @@ retry: lock_page(page); + if (unlikely(page->mapping != mapping)) { + unlock_page(page); + continue; + } + + if (unlikely(is_range) && page->index > end) { + done = 1; + unlock_page(page); + continue; + } + if (wbc->sync_mode != WB_SYNC_NONE) wait_on_page_writeback(page); - if (page->mapping != mapping || PageWriteback(page) || + if (PageWriteback(page) || !clear_page_dirty_for_io(page)) { unlock_page(page); continue; @@ -701,7 +721,8 @@ retry: index = 0; goto retry; } - mapping->writeback_index = index; + if (!is_range) + mapping->writeback_index = index; if (bio) mpage_bio_submit(WRITE, bio); return ret; diff -puN include/linux/writeback.h~writepages-range include/linux/writeback.h --- linux-2.6.8-rc2/include/linux/writeback.h~writepages-range 2004-08-01 12:30:15.000000000 +0530 +++ linux-2.6.8-rc2-suparna/include/linux/writeback.h 2004-08-01 12:30:15.000000000 +0530 @@ -29,7 +29,9 @@ enum writeback_sync_modes { }; /* - * A control structure which tells the writeback code what to do + * A control structure which tells the writeback code what to do. These are + * always on the stack, and hence need no locking. They are always initialised + * in a manner such that unspecified fields are set to zero. */ struct writeback_control { struct backing_dev_info *bdi; /* If !NULL, only write back this @@ -40,10 +42,19 @@ struct writeback_control { long nr_to_write; /* Write this many pages, and decrement this for each page written */ long pages_skipped; /* Pages which were not written */ - int nonblocking; /* Don't get stuck on request queues */ - int encountered_congestion; /* An output: a queue is full */ - int for_kupdate; /* A kupdate writeback */ - int for_reclaim; /* Invoked from the page allocator */ + + /* + * For a_ops->writepages(): is start or end are non-zero then this is + * a hint that the filesystem need only write out the pages inside that + * byterange. The byte at `end' is included in the writeout request. + */ + loff_t start; + loff_t end; + + int nonblocking:1; /* Don't get stuck on request queues */ + int encountered_congestion:1; /* An output: a queue is full */ + int for_kupdate:1; /* A kupdate writeback */ + int for_reclaim:1; /* Invoked from the page allocator */ }; /* _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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