| Message ID | 20200125013553.24899-7-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Change readahead API | expand |
On Fri, Jan 24, 2020 at 05:35:47PM -0800, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > Use the new readahead operation in btrfs > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Cc: linux-btrfs@vger.kernel.org > --- > fs/btrfs/extent_io.c | 15 ++++----------- > fs/btrfs/extent_io.h | 2 +- > fs/btrfs/inode.c | 18 +++++++++--------- > 3 files changed, 14 insertions(+), 21 deletions(-) > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index 2f4802f405a2..b1e2acbec165 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping, > return ret; > } > > -int extent_readpages(struct address_space *mapping, struct list_head *pages, > +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, > unsigned nr_pages) > { > struct bio *bio = NULL; > @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages, > int nr = 0; > u64 prev_em_start = (u64)-1; > > - while (!list_empty(pages)) { > + while (nr_pages) { > u64 contig_end = 0; > > - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) { > - struct page *page = lru_to_page(pages); > + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) { What is stopping nr_pages from going negative here, and then looping forever on the outer nr_pages loop? Perhaps "while(nr_pages > 0) {" would be better there? -Dave.
On Wed, Jan 29, 2020 at 11:46:09AM +1100, Dave Chinner wrote: > On Fri, Jan 24, 2020 at 05:35:47PM -0800, Matthew Wilcox wrote: > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > Use the new readahead operation in btrfs > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > Cc: linux-btrfs@vger.kernel.org > > --- > > fs/btrfs/extent_io.c | 15 ++++----------- > > fs/btrfs/extent_io.h | 2 +- > > fs/btrfs/inode.c | 18 +++++++++--------- > > 3 files changed, 14 insertions(+), 21 deletions(-) > > > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > > index 2f4802f405a2..b1e2acbec165 100644 > > --- a/fs/btrfs/extent_io.c > > +++ b/fs/btrfs/extent_io.c > > @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping, > > return ret; > > } > > > > -int extent_readpages(struct address_space *mapping, struct list_head *pages, > > +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, > > unsigned nr_pages) > > { > > struct bio *bio = NULL; > > @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages, > > int nr = 0; > > u64 prev_em_start = (u64)-1; > > > > - while (!list_empty(pages)) { > > + while (nr_pages) { > > u64 contig_end = 0; > > > > - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) { > > - struct page *page = lru_to_page(pages); > > + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) { > > What is stopping nr_pages from going negative here, and then looping > forever on the outer nr_pages loop? Perhaps "while(nr_pages > 0) {" > would be better there? Ugh, nr_pages is unsigned, so that's no good. Maybe make this a more conventional loop ... while (nr_pages) { u64 contig_end = 0; for (nr = 0; nr < ARRAY_SIZE(pagepool); nr++) { struct page *page = readahead_page(mapping, start++); prefetchw(&page->flags); pagepool[nr] = page; contig_end = page_offset(page) + PAGE_SIZE - 1; if (--nr_pages == 0) break; }
On Thu, Jan 30, 2020 at 12:09:39AM -0800, Matthew Wilcox wrote: > On Wed, Jan 29, 2020 at 11:46:09AM +1100, Dave Chinner wrote: > > On Fri, Jan 24, 2020 at 05:35:47PM -0800, Matthew Wilcox wrote: > > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org> > > > > > > Use the new readahead operation in btrfs > > > > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > > Cc: linux-btrfs@vger.kernel.org > > > --- > > > fs/btrfs/extent_io.c | 15 ++++----------- > > > fs/btrfs/extent_io.h | 2 +- > > > fs/btrfs/inode.c | 18 +++++++++--------- > > > 3 files changed, 14 insertions(+), 21 deletions(-) > > > > > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > > > index 2f4802f405a2..b1e2acbec165 100644 > > > --- a/fs/btrfs/extent_io.c > > > +++ b/fs/btrfs/extent_io.c > > > @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping, > > > return ret; > > > } > > > > > > -int extent_readpages(struct address_space *mapping, struct list_head *pages, > > > +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, > > > unsigned nr_pages) > > > { > > > struct bio *bio = NULL; > > > @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages, > > > int nr = 0; > > > u64 prev_em_start = (u64)-1; > > > > > > - while (!list_empty(pages)) { > > > + while (nr_pages) { > > > u64 contig_end = 0; > > > > > > - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) { > > > - struct page *page = lru_to_page(pages); > > > + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) { > > > > What is stopping nr_pages from going negative here, and then looping > > forever on the outer nr_pages loop? Perhaps "while(nr_pages > 0) {" > > would be better there? > > Ugh, nr_pages is unsigned, so that's no good. Maybe make this a more > conventional loop ... > > while (nr_pages) { > u64 contig_end = 0; > > for (nr = 0; nr < ARRAY_SIZE(pagepool); nr++) { > struct page *page = readahead_page(mapping, start++); > > prefetchw(&page->flags); > pagepool[nr] = page; > contig_end = page_offset(page) + PAGE_SIZE - 1; > if (--nr_pages == 0) > break; > } Looks like it solves the problem :) Cheers, Dave.
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 2f4802f405a2..b1e2acbec165 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping, return ret; } -int extent_readpages(struct address_space *mapping, struct list_head *pages, +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, unsigned nr_pages) { struct bio *bio = NULL; @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages, int nr = 0; u64 prev_em_start = (u64)-1; - while (!list_empty(pages)) { + while (nr_pages) { u64 contig_end = 0; - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) { - struct page *page = lru_to_page(pages); + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) { + struct page *page = readahead_page(mapping, start++); prefetchw(&page->flags); - list_del(&page->lru); - if (add_to_page_cache_lru(page, mapping, page->index, - readahead_gfp_mask(mapping))) { - put_page(page); - break; - } - pagepool[nr++] = page; contig_end = page_offset(page) + PAGE_SIZE - 1; } diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index a8551a1f56e2..d0f154766a02 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -200,7 +200,7 @@ int extent_writepages(struct address_space *mapping, struct writeback_control *wbc); int btree_write_cache_pages(struct address_space *mapping, struct writeback_control *wbc); -int extent_readpages(struct address_space *mapping, struct list_head *pages, +unsigned extent_readahead(struct address_space *mapping, pgoff_t start, unsigned nr_pages); int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, __u64 start, __u64 len); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index c70baafb2a39..4f223b4f7dff 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5395,8 +5395,8 @@ static void evict_inode_truncate_pages(struct inode *inode) /* * Keep looping until we have no more ranges in the io tree. - * We can have ongoing bios started by readpages (called from readahead) - * that have their endio callback (extent_io.c:end_bio_extent_readpage) + * We can have ongoing bios started by readahead that have + * their endio callback (extent_io.c:end_bio_extent_readpage) * still in progress (unlocked the pages in the bio but did not yet * unlocked the ranges in the io tree). Therefore this means some * ranges can still be locked and eviction started because before @@ -7586,11 +7586,11 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend, * for it to complete) and then invalidate the pages for * this range (through invalidate_inode_pages2_range()), * but that can lead us to a deadlock with a concurrent - * call to readpages() (a buffered read or a defrag call + * call to readahead (a buffered read or a defrag call * triggered a readahead) on a page lock due to an * ordered dio extent we created before but did not have * yet a corresponding bio submitted (whence it can not - * complete), which makes readpages() wait for that + * complete), which makes readahead wait for that * ordered extent to complete while holding a lock on * that page. */ @@ -8829,11 +8829,11 @@ static int btrfs_writepages(struct address_space *mapping, return extent_writepages(mapping, wbc); } -static int -btrfs_readpages(struct file *file, struct address_space *mapping, - struct list_head *pages, unsigned nr_pages) +static unsigned +btrfs_readahead(struct file *file, struct address_space *mapping, + pgoff_t start, unsigned nr_pages) { - return extent_readpages(mapping, pages, nr_pages); + return extent_readahead(mapping, start, nr_pages); } static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags) @@ -11045,7 +11045,7 @@ static const struct address_space_operations btrfs_aops = { .readpage = btrfs_readpage, .writepage = btrfs_writepage, .writepages = btrfs_writepages, - .readpages = btrfs_readpages, + .readahead = btrfs_readahead, .direct_IO = btrfs_direct_IO, .invalidatepage = btrfs_invalidatepage, .releasepage = btrfs_releasepage,