Messages in this thread Patch in this message | | | From | Gao Xiang <> | Subject | [RFC PATCH 2/2] erofs: directly traverse pages in z_erofs_readahead() | Date | Tue, 6 Jul 2021 02:32:53 +0800 |
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In that way, pages can be accessed directly with xarray.
Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Gao Xiang <xiang@kernel.org> --- Just an open-coded PoC one, since that is what EROFS actually needs but without the iteration API (see [PATCH 1/2] as well.)
fs/erofs/zdata.c | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 054b9839e9db..210b2965ecc4 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1416,7 +1416,8 @@ static void z_erofs_readahead(struct readahead_control *rac) bool sync = (sbi->ctx.readahead_sync_decompress && nr_pages <= sbi->ctx.max_sync_decompress_pages); struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode); - struct page *page, *head = NULL; + struct page *page; + pgoff_t index; LIST_HEAD(pagepool); trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false); @@ -1434,26 +1435,19 @@ static void z_erofs_readahead(struct readahead_control *rac) * 2) submission chain can be then in the forward order since * pclusters are all inserted at head. */ - while ((page = readahead_page(rac))) { - prefetchw(&page->flags); - - /* - * A pure asynchronous readahead is indicated if - * a PG_readahead marked page is hitted at first. - * Let's also do asynchronous decompression for this case. - */ - sync &= !(PageReadahead(page) && !head); - - set_page_private(page, (unsigned long)head); - head = page; - } - - while (head) { - struct page *page = head; + index = rac->_index + rac->_nr_pages; + while (rac->_nr_pages) { + struct page *head; int err; - /* traversal in reverse order */ - head = (void *)page_private(page); + --rac->_nr_pages; + page = xa_load(&rac->mapping->i_pages, --index); + /* XXX: very incomplete thp support */ + head = thp_head(page); + if (head != page) { + index -= page->index - head->index; + page = head; + } err = z_erofs_do_read_page(&f, page, &pagepool); if (err) -- 2.20.1
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