linux-erofs.lists.ozlabs.org archive mirror
 help / color / mirror / Atom feed
* [PATCH v3] iomap: support tail packing inline read
@ 2021-07-19 14:47 Gao Xiang
  2021-07-19 15:02 ` Matthew Wilcox
                   ` (2 more replies)
  0 siblings, 3 replies; 13+ messages in thread
From: Gao Xiang @ 2021-07-19 14:47 UTC (permalink / raw)
  To: linux-erofs, linux-fsdevel
  Cc: Darrick J . Wong, Andreas Gruenbacher, LKML, Matthew Wilcox,
	Christoph Hellwig

This tries to add tail packing inline read to iomap, which can support
several inline tail blocks. Similar to the previous approach, it cleans
post-EOF in one iteration.

The write path remains untouched since EROFS cannot be used for testing.
It'd be better to be implemented if upcoming real users care rather than
leave untested dead code around.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
v2: https://lore.kernel.org/r/YPLdSja%2F4FBsjss%2F@B-P7TQMD6M-0146.local/
changes since v2:
 - update suggestion from Christoph:
    https://lore.kernel.org/r/YPVe41YqpfGLNsBS@infradead.org/

Hi Andreas,
would you mind test on the gfs2 side? Thanks in advance!

Thanks,
Gao Xiang

 fs/iomap/buffered-io.c | 50 ++++++++++++++++++++++++++----------------
 fs/iomap/direct-io.c   | 11 ++++++----
 2 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 87ccb3438bec..cac8a88660d8 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -207,23 +207,22 @@ struct iomap_readpage_ctx {
 
 static void
 iomap_read_inline_data(struct inode *inode, struct page *page,
-		struct iomap *iomap)
+		struct iomap *iomap, loff_t pos)
 {
-	size_t size = i_size_read(inode);
+	unsigned int size, poff = offset_in_page(pos);
 	void *addr;
 
-	if (PageUptodate(page))
-		return;
-
-	BUG_ON(page_has_private(page));
-	BUG_ON(page->index);
-	BUG_ON(size > PAGE_SIZE - offset_in_page(iomap->inline_data));
+	/* inline source data must be inside a single page */
+	BUG_ON(iomap->length > PAGE_SIZE - offset_in_page(iomap->inline_data));
+	/* handle tail-packing blocks cross the current page into the next */
+	size = min_t(unsigned int, iomap->length + pos - iomap->offset,
+		     PAGE_SIZE - poff);
 
 	addr = kmap_atomic(page);
-	memcpy(addr, iomap->inline_data, size);
-	memset(addr + size, 0, PAGE_SIZE - size);
+	memcpy(addr + poff, iomap->inline_data - iomap->offset + pos, size);
+	memset(addr + poff + size, 0, PAGE_SIZE - poff - size);
 	kunmap_atomic(addr);
-	SetPageUptodate(page);
+	iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
 }
 
 static inline bool iomap_block_needs_zeroing(struct inode *inode,
@@ -246,18 +245,19 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	unsigned poff, plen;
 	sector_t sector;
 
-	if (iomap->type == IOMAP_INLINE) {
-		WARN_ON_ONCE(pos);
-		iomap_read_inline_data(inode, page, iomap);
-		return PAGE_SIZE;
-	}
-
-	/* zero post-eof blocks as the page may be mapped */
 	iop = iomap_page_create(inode, page);
+	/* needs to skip some leading uptodated blocks */
 	iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
 	if (plen == 0)
 		goto done;
 
+	if (iomap->type == IOMAP_INLINE) {
+		iomap_read_inline_data(inode, page, iomap, pos);
+		plen = PAGE_SIZE - poff;
+		goto done;
+	}
+
+	/* zero post-eof blocks as the page may be mapped */
 	if (iomap_block_needs_zeroing(inode, iomap, pos)) {
 		zero_user(page, poff, plen);
 		iomap_set_range_uptodate(page, poff, plen);
@@ -589,6 +589,18 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
 	return 0;
 }
 
+static int iomap_write_begin_inline(struct inode *inode, loff_t pos,
+		struct page *page, struct iomap *srcmap)
+{
+	/* needs more work for the tailpacking case, disable for now */
+	if (WARN_ON_ONCE(pos != 0))
+		return -EIO;
+	if (PageUptodate(page))
+		return 0;
+	iomap_read_inline_data(inode, page, srcmap, pos);
+	return 0;
+}
+
 static int
 iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, struct iomap *iomap, struct iomap *srcmap)
@@ -618,7 +630,7 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
 	}
 
 	if (srcmap->type == IOMAP_INLINE)
-		iomap_read_inline_data(inode, page, srcmap);
+		status = iomap_write_begin_inline(inode, pos, page, srcmap);
 	else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
 		status = __block_write_begin_int(page, pos, len, NULL, srcmap);
 	else
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 9398b8c31323..ee6309967b77 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -379,22 +379,25 @@ iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
 {
 	struct iov_iter *iter = dio->submit.iter;
 	size_t copied;
+	void *dst = iomap->inline_data + pos - iomap->offset;
 
-	BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
+	/* inline data must be inside a single page */
+	BUG_ON(length > PAGE_SIZE - offset_in_page(iomap->inline_data));
 
 	if (dio->flags & IOMAP_DIO_WRITE) {
 		loff_t size = inode->i_size;
 
 		if (pos > size)
-			memset(iomap->inline_data + size, 0, pos - size);
-		copied = copy_from_iter(iomap->inline_data + pos, length, iter);
+			memset(iomap->inline_data + size - iomap->offset,
+			       0, pos - size);
+		copied = copy_from_iter(dst, length, iter);
 		if (copied) {
 			if (pos + copied > size)
 				i_size_write(inode, pos + copied);
 			mark_inode_dirty(inode);
 		}
 	} else {
-		copied = copy_to_iter(iomap->inline_data + pos, length, iter);
+		copied = copy_to_iter(dst, length, iter);
 	}
 	dio->size += copied;
 	return copied;
-- 
2.24.4


^ permalink raw reply	[flat|nested] 13+ messages in thread

end of thread, other threads:[~2021-07-20 12:24 UTC | newest]

Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-07-19 14:47 [PATCH v3] iomap: support tail packing inline read Gao Xiang
2021-07-19 15:02 ` Matthew Wilcox
2021-07-19 15:13   ` Christoph Hellwig
2021-07-19 16:11     ` Gao Xiang
2021-07-19 16:31       ` Matthew Wilcox
2021-07-19 16:45         ` Gao Xiang
2021-07-19 15:29   ` Gao Xiang
2021-07-19 15:31     ` Andreas Grünbacher
2021-07-19 15:36       ` Gao Xiang
2021-07-20 11:23 ` Andreas Grünbacher
2021-07-20 12:10   ` Gao Xiang
2021-07-20 11:34 ` Andreas Grünbacher
2021-07-20 12:23   ` Gao Xiang

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).