Messages in this thread Patches in this message | | | Subject | Re: [PATCH] fs-writeback: Flush plug before next iteration in wb_writeback() | From | Zhihao Cheng <> | Date | Fri, 15 Apr 2022 16:39:12 +0800 |
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在 2022/4/15 14:39, Christoph Hellwig 写道: Hi, Christoph > This basically removes plugging entirely, so we might as well stop > adding the plug if we can't solve it any other way. But it seems > like that fake progress needs to be fixed instead. > Maybe there is a more ideal solution: diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index e524c0a1749c..9723f77841f8 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1855,7 +1855,7 @@ static long writeback_sb_inodes(struct super_block *sb,
wbc_detach_inode(&wbc); work->nr_pages -= write_chunk - wbc.nr_to_write; - wrote += write_chunk - wbc.nr_to_write; + wrote += write_chunk - wbc.nr_to_write - wbc.pages_skipped;
if (need_resched()) { /* , or following is better(It looks awkward.):
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index e524c0a1749c..5f310e53bf1e 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1780,6 +1780,7 @@ static long writeback_sb_inodes(struct super_block *sb, while (!list_empty(&wb->b_io)) { struct inode *inode = wb_inode(wb->b_io.prev); struct bdi_writeback *tmp_wb; + long tmp_wrote;
if (inode->i_sb != sb) { if (work->sb) { @@ -1854,8 +1855,11 @@ static long writeback_sb_inodes(struct super_block *sb, __writeback_single_inode(inode, &wbc);
wbc_detach_inode(&wbc); - work->nr_pages -= write_chunk - wbc.nr_to_write; - wrote += write_chunk - wbc.nr_to_write; + tmp_wrote = write_chunk - wbc.nr_to_write >= wbc.pages_skipped ? + write_chunk - wbc.nr_to_write - wbc.pages_skipped : + write_chunk - wbc.nr_to_write;workaround + work->nr_pages -= tmp_wrote; + wrote += tmp_wrote;
if (need_resched()) { /* It depends on how specific filesystem behaves after invoking redirty_page_for_writepage(). Most filesystems return AOP_WRITEPAGE_ACTIVATE or 0 after invoking redirty_page_for_writepage() in writepage, but there still exist accidential examples: 1. metapage_writepage() could returns -EIO after redirty_page_for_writepage() 2. ext4_writepage() could returns -ENOMEM after redirty_page_for_writepage()
write_cache_pages error = (*writepage)(page, wbc, data); if (unlikely(error)) { ... break; } --wbc->nr_to_write // Skip if 'error < 0'. And if writepage invokes redirty_page_for_writepage(), wrote could be negative.
I think the root cause is fsync gets buffer head's lock without locking corresponding page, fixing 'progess' and flushing plug are both workarounds.
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