[PATCH, RFC 11/16] thp, mm: naive support of thp in generic read/write routines
From: Kirill A. Shutemov <hidden>
Date: 2013-01-28 09:24:23
Also in:
linux-fsdevel, lkml
Subsystem:
memory management, page cache, the rest · Maintainers:
Andrew Morton, Matthew Wilcox, Jan Kara, Linus Torvalds
From: "Kirill A. Shutemov" <redacted> For now we still write/read at most PAGE_CACHE_SIZE bytes a time. This implementation doesn't cover address spaces with backing store. Signed-off-by: Kirill A. Shutemov <redacted> --- mm/filemap.c | 35 ++++++++++++++++++++++++++++++----- 1 file changed, 30 insertions(+), 5 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 68e47e4..a7331fb 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -1161,12 +1161,23 @@ find_page: if (unlikely(page == NULL)) goto no_cached_page; } + if (PageTransTail(page)) { + page_cache_release(page); + page = find_get_page(mapping, + index & ~HPAGE_CACHE_INDEX_MASK); + if (!PageTransHuge(page)) { + page_cache_release(page); + goto find_page; + } + } if (PageReadahead(page)) { + BUG_ON(PageTransHuge(page)); page_cache_async_readahead(mapping, ra, filp, page, index, last_index - index); } if (!PageUptodate(page)) { + BUG_ON(PageTransHuge(page)); if (inode->i_blkbits == PAGE_CACHE_SHIFT || !mapping->a_ops->is_partially_uptodate) goto page_not_up_to_date;
@@ -1208,18 +1219,25 @@ page_ok: } nr = nr - offset; + /* Recalculate offset in page if we've got a huge page */ + if (PageTransHuge(page)) { + offset = (((loff_t)index << PAGE_CACHE_SHIFT) + offset); + offset &= ~HPAGE_PMD_MASK; + } + /* If users can be writing to this page using arbitrary * virtual addresses, take care about potential aliasing * before reading the page on the kernel side. */ if (mapping_writably_mapped(mapping)) - flush_dcache_page(page); + flush_dcache_page(page + (offset >> PAGE_CACHE_SHIFT)); /* * When a sequential read accesses a page several times, * only mark it as accessed the first time. */ - if (prev_index != index || offset != prev_offset) + if (prev_index != index || + (offset & ~PAGE_CACHE_MASK) != prev_offset) mark_page_accessed(page); prev_index = index;
@@ -1234,8 +1252,9 @@ page_ok: * "pos" here (the actor routine has to update the user buffer * pointers and the remaining count). */ - ret = file_read_actor(desc, page, offset, nr); - offset += ret; + ret = file_read_actor(desc, page + (offset >> PAGE_CACHE_SHIFT), + offset & ~PAGE_CACHE_MASK, nr); + offset = (offset & ~PAGE_CACHE_MASK) + ret; index += offset >> PAGE_CACHE_SHIFT; offset &= ~PAGE_CACHE_MASK; prev_offset = offset;
@@ -2433,8 +2452,13 @@ again: if (mapping_writably_mapped(mapping)) flush_dcache_page(page); + if (PageTransHuge(page)) + offset = pos & ~HPAGE_PMD_MASK; + pagefault_disable(); - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); + copied = iov_iter_copy_from_user_atomic( + page + (offset >> PAGE_CACHE_SHIFT), + i, offset & ~PAGE_CACHE_MASK, bytes); pagefault_enable(); flush_dcache_page(page);
@@ -2457,6 +2481,7 @@ again: * because not all segments in the iov can be copied at * once without a pagefault. */ + offset = pos & ~PAGE_CACHE_MASK; bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset, iov_iter_single_seg_count(i)); goto again;
--
1.7.10.4
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