linux-ext4 - [PATCH 1/2] ext4: fix seek

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Message-Id: <1418918346-9546-1-git-send-email-dmonakhov@openvz.org>
Date:	Thu, 18 Dec 2014 19:59:05 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	linux-ext4@...r.kernel.org
Cc:	tytso@....edu, Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH 1/2] ext4: fix seek_data cleanup

- Remove usless condition page_has_buffers(). We already checked that previously.

- The goal of ext4_find_unwritten_pgoff() is to distinguish uninitialized data
  from initialized or delayed ones so check (buffer_uptodate() || buffer_unwritten() is
  not correct. Data is delayed if bh_uptodate && (bh_delayed || bh_async_write)
- Rename ext4_find_unwritten_pgoff -> ext4_find_delayed_pgoff
- Fix seek_data/seek_hole for case blk_sz != pg_sz.

tested on following configurations
xfstest-blk conf: ext3, ext3-1k, ext3-1k-da, 1k, 4k
test: generic/285

Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
---
 fs/ext4/file.c |   58 ++++++++++++++++++++++++++++---------------------------
 1 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 513c12c..8ec48a4 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -273,19 +273,19 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
  * we determine this extent as a data or a hole according to whether the
  * page cache has data or not.
  */
-static int ext4_find_unwritten_pgoff(struct inode *inode, int whence,
-				     loff_t endoff, loff_t *offset)
+static int ext4_find_delayed_pgoff(struct inode *inode, int whence,
+			   loff_t endoff, loff_t *offset)
 {
 	struct pagevec pvec;
 	pgoff_t index;
 	pgoff_t end;
 	loff_t startoff;
 	loff_t lastoff;
+	loff_t last_data;
 	int found = 0;
 
 	startoff = *offset;
-	lastoff = startoff;
-
+	last_data = lastoff = startoff;
 
 	index = startoff >> PAGE_CACHE_SHIFT;
 	end = endoff >> PAGE_CACHE_SHIFT;
@@ -350,30 +350,32 @@ static int ext4_find_unwritten_pgoff(struct inode *inode, int whence,
 				unlock_page(page);
 				continue;
 			}
-
-			if (page_has_buffers(page)) {
-				lastoff = page_offset(page);
-				bh = head = page_buffers(page);
-				do {
-					if (buffer_uptodate(bh) ||
-					    buffer_unwritten(bh)) {
-						if (whence == SEEK_DATA)
-							found = 1;
-					} else {
-						if (whence == SEEK_HOLE)
-							found = 1;
+			lastoff = page_offset(page);
+			bh = head = page_buffers(page);
+			do {
+				if (buffer_uptodate(bh) &&
+				    (buffer_dirty(bh) ||
+				     buffer_async_write(bh))) {
+					last_data = lastoff + bh->b_size;
+					if (whence == SEEK_DATA &&
+					    lastoff + bh->b_size > startoff)
+						found = 1;
+				} else {
+					if (whence == SEEK_HOLE &&
+					    lastoff + bh->b_size > startoff) {
+						lastoff = last_data;
+						found = 1;
 					}
-					if (found) {
-						*offset = max_t(loff_t,
+				}
+				if (found) {
+					*offset = max_t(loff_t,
 							startoff, lastoff);
-						unlock_page(page);
-						goto out;
-					}
-					lastoff += bh->b_size;
-					bh = bh->b_this_page;
-				} while (bh != head);
-			}
-
+					unlock_page(page);
+					goto out;
+				}
+				lastoff += bh->b_size;
+				bh = bh->b_this_page;
+			} while (bh != head);
 			lastoff = page_offset(page) + PAGE_SIZE;
 			unlock_page(page);
 		}
@@ -450,7 +452,7 @@ static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
 			 * it will be as a data or a hole according to page
 			 * cache that has data or not.
 			 */
-			if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
+			if (ext4_find_delayed_pgoff(inode, SEEK_DATA,
 						      next, &offset))
 				goto out;
 
@@ -524,7 +526,7 @@ static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
 			 * it will be as a data or a hole according to page
 			 * cache that has data or not.
 			 */
-			if (ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
+			if (ext4_find_delayed_pgoff(inode, SEEK_HOLE,
 						      next, &offset))
 				goto out;
 
-- 
1.7.1

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