linux-ext4 - [PATCH 02/15 v2] jbd2: implement jbd2_journal_invalidatepage

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Message-Id: <1346451711-1931-3-git-send-email-lczerner@redhat.com>
Date:	Fri, 31 Aug 2012 18:21:38 -0400
From:	Lukas Czerner <lczerner@...hat.com>
To:	linux-fsdevel@...r.kernel.org
Cc:	linux-ext4@...r.kernel.org, tytso@....edu, hughd@...gle.com,
	linux-mm@...ck.org, Lukas Czerner <lczerner@...hat.com>
Subject: [PATCH 02/15 v2] jbd2: implement jbd2_journal_invalidatepage_range

mm now supports invalidatepage_range address space operation and there
are two file system using jbd2 also implementing punch hole feature
which can benefit from this. We need to implement the same thing for
jbd2 layer in order to allow those file system take benefit of this
functionality.

With new function jbd2_journal_invalidatepage_range() we can now specify
length to invalidate, rather than assuming invalidate to the end of the
page.

Signed-off-by: Lukas Czerner <lczerner@...hat.com>
---
 fs/jbd2/journal.c     |    1 +
 fs/jbd2/transaction.c |   19 +++++++++++++++++--
 include/linux/jbd2.h  |    2 ++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index e149b99..e4618e9 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -86,6 +86,7 @@ EXPORT_SYMBOL(jbd2_journal_force_commit_nested);
 EXPORT_SYMBOL(jbd2_journal_wipe);
 EXPORT_SYMBOL(jbd2_journal_blocks_per_page);
 EXPORT_SYMBOL(jbd2_journal_invalidatepage);
+EXPORT_SYMBOL(jbd2_journal_invalidatepage_range);
 EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
 EXPORT_SYMBOL(jbd2_journal_force_commit);
 EXPORT_SYMBOL(jbd2_journal_file_inode);
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index fb1ab953..65c1374 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1993,10 +1993,20 @@ zap_buffer_unlocked:
  *
  */
 void jbd2_journal_invalidatepage(journal_t *journal,
-		      struct page *page,
-		      unsigned long offset)
+				 struct page *page,
+				 unsigned long offset)
+{
+	jbd2_journal_invalidatepage_range(journal, page, offset,
+					  PAGE_CACHE_SIZE - offset);
+}
+
+void jbd2_journal_invalidatepage_range(journal_t *journal,
+				       struct page *page,
+				       unsigned int offset,
+				       unsigned int length)
 {
 	struct buffer_head *head, *bh, *next;
+	unsigned int stop = offset + length;
 	unsigned int curr_off = 0;
 	int may_free = 1;
 
@@ -2005,6 +2015,8 @@ void jbd2_journal_invalidatepage(journal_t *journal,
 	if (!page_has_buffers(page))
 		return;
 
+	BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
+
 	/* We will potentially be playing with lists other than just the
 	 * data lists (especially for journaled data mode), so be
 	 * cautious in our locking. */
@@ -2014,6 +2026,9 @@ void jbd2_journal_invalidatepage(journal_t *journal,
 		unsigned int next_off = curr_off + bh->b_size;
 		next = bh->b_this_page;
 
+		if (next_off > stop)
+			return;
+
 		if (offset <= curr_off) {
 			/* This block is wholly outside the truncation point */
 			lock_buffer(bh);
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 3efc43f..21288fa 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1101,6 +1101,8 @@ extern int	 jbd2_journal_forget (handle_t *, struct buffer_head *);
 extern void	 journal_sync_buffer (struct buffer_head *);
 extern void	 jbd2_journal_invalidatepage(journal_t *,
 				struct page *, unsigned long);
+extern void	 jbd2_journal_invalidatepage_range(journal_t *, struct page *,
+						   unsigned int, unsigned int);
 extern int	 jbd2_journal_try_to_free_buffers(journal_t *, struct page *, gfp_t);
 extern int	 jbd2_journal_stop(handle_t *);
 extern int	 jbd2_journal_flush (journal_t *);
-- 
1.7.7.6

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