linux-ext4 - [PATCH] ext4: restart ext4_ext_remove_space() after transaction restart

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Message-Id: <1271910671-16627-1-git-send-email-dmonakhov@openvz.org>
Date:	Thu, 22 Apr 2010 08:31:11 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	linux-ext4@...r.kernel.org
Cc:	jack@...e.cz, aneesh.kumar@...ux.vnet.ibm.com, tytso@....ed,
	Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH] ext4: restart ext4_ext_remove_space() after transaction restart

If i_data_sem was internally dropped due to transaction restart, it is
necessary to restart path look-up because extents tree was possibly
modified by ext4_get_block().

https://bugzilla.kernel.org/show_bug.cgi?id=15827

Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
---
 fs/ext4/ext4.h    |    1 +
 fs/ext4/extents.c |   18 +++++++++++++-----
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 6641c58..c69efb2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1089,6 +1089,7 @@ enum {
 	EXT4_STATE_DA_ALLOC_CLOSE,	/* Alloc DA blks on close */
 	EXT4_STATE_EXT_MIGRATE,		/* Inode is migrating */
 	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/
+	EXT4_STATE_EXT_TRUNC,		/* truncate is in progress, modified under i_data_sem */
 };
 
 #define EXT4_INODE_BIT_FNS(name, field)					\
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4fa103c..6856272 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -107,11 +107,8 @@ static int ext4_ext_truncate_extend_restart(handle_t *handle,
 	if (err <= 0)
 		return err;
 	err = ext4_truncate_restart_trans(handle, inode, needed);
-	/*
-	 * We have dropped i_data_sem so someone might have cached again
-	 * an extent we are going to truncate.
-	 */
-	ext4_ext_invalidate_cache(inode);
+	if (!err && !ext4_test_inode_state(inode, EXT4_STATE_EXT_TRUNC))
+		err = -EAGAIN;
 
 	return err;
 }
@@ -2370,12 +2367,15 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
 	if (IS_ERR(handle))
 		return PTR_ERR(handle);
 
+again:
 	ext4_ext_invalidate_cache(inode);
 
 	/*
 	 * We start scanning from right side, freeing all the blocks
 	 * after i_size and walking into the tree depth-wise.
 	 */
+	ext4_set_inode_state(inode, EXT4_STATE_EXT_TRUNC);
+	depth = ext_depth(inode);
 	path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
 	if (path == NULL) {
 		ext4_journal_stop(handle);
@@ -2480,6 +2480,11 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start)
 out:
 	ext4_ext_drop_refs(path);
 	kfree(path);
+	if (err == EAGAIN) {
+		err = 0;
+		goto again;
+	}
+	ext4_clear_inode_state(inode, EXT4_STATE_EXT_TRUNC);
 	ext4_journal_stop(handle);
 
 	return err;
@@ -3338,6 +3343,9 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
 	ext_debug("blocks %u/%u requested for inode %lu\n",
 			iblock, max_blocks, inode->i_ino);
 
+	if (unlikely((flags & EXT4_GET_BLOCKS_CREATE)) &&
+		ext4_test_inode_state(inode, EXT4_STATE_EXT_TRUNC))
+		ext4_clear_inode_state(inode, EXT4_STATE_EXT_TRUNC);
 	/* check in cache */
 	cache_type = ext4_ext_in_cache(inode, iblock, &newex);
 	if (cache_type) {
-- 
1.6.6.1

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