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Date: Thu, 7 Aug 2014 11:35:50 +0800
From: Zheng Liu <gnehzuil.liu@...il.com>
To: linux-ext4@...r.kernel.org
Cc: "Theodore Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
Jan Kara <jack@...e.cz>, Zheng Liu <wenqing.lz@...bao.com>
Subject: [PATCH v3 3/6] ext4: cache extent hole in extent status tree for ext4_da_map_blocks()
From: Zheng Liu <wenqing.lz@...bao.com>
Currently extent status tree doesn't cache extent hole when a write
looks up in extent tree to make sure whether a block has been allocated
or not. In this case, we don't put extent hole in extent cache because
later this extent might be removed and a new delayed extent might be
added back. But it will cause a defect when we do a lot of writes.
If we don't put extent hole in extent cache, the following writes also
need to access extent tree to look at whether or not a block has been
allocated. It brings a cache miss. This commit fixes this defect.
Meanwhile, if an inode has no any extent, this extent hole also will
be cached.
Cc: "Theodore Ts'o" <tytso@....edu>
Cc: Andreas Dilger <adilger.kernel@...ger.ca>
Cc: Jan Kara <jack@...e.cz>
Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
---
fs/ext4/ext4.h | 4 +---
fs/ext4/extents.c | 23 +++++++++--------------
fs/ext4/inode.c | 6 ++----
include/trace/events/ext4.h | 3 +--
4 files changed, 13 insertions(+), 23 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 6f294d3..7df9220 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -565,10 +565,8 @@ enum {
#define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080
/* Do not take i_data_sem locking in ext4_map_blocks */
#define EXT4_GET_BLOCKS_NO_LOCK 0x0100
- /* Do not put hole in extent cache */
-#define EXT4_GET_BLOCKS_NO_PUT_HOLE 0x0200
/* Convert written extents to unwritten */
-#define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN 0x0400
+#define EXT4_GET_BLOCKS_CONVERT_UNWRITTEN 0x0200
/*
* The bit position of these flags must not overlap with any of the
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 76c2df3..6463d34 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2284,16 +2284,15 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
ext4_lblk_t block)
{
int depth = ext_depth(inode);
- unsigned long len = 0;
- ext4_lblk_t lblock = 0;
+ unsigned long len;
+ ext4_lblk_t lblock;
struct ext4_extent *ex;
ex = path[depth].p_ext;
if (ex == NULL) {
- /*
- * there is no extent yet, so gap is [0;-] and we
- * don't cache it
- */
+ /* there is no extent yet, so gap is [0;-] */
+ lblock = 0;
+ len = EXT_MAX_BLOCKS;
ext_debug("cache gap(whole file):");
} else if (block < le32_to_cpu(ex->ee_block)) {
lblock = block;
@@ -2302,9 +2301,6 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
block,
le32_to_cpu(ex->ee_block),
ext4_ext_get_actual_len(ex));
- if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
- ext4_es_insert_extent(inode, lblock, len, ~0,
- EXTENT_STATUS_HOLE);
} else if (block >= le32_to_cpu(ex->ee_block)
+ ext4_ext_get_actual_len(ex)) {
ext4_lblk_t next;
@@ -2318,14 +2314,14 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
block);
BUG_ON(next == lblock);
len = next - lblock;
- if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
- ext4_es_insert_extent(inode, lblock, len, ~0,
- EXTENT_STATUS_HOLE);
} else {
BUG();
}
ext_debug(" -> %u:%lu\n", lblock, len);
+ if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
+ ext4_es_insert_extent(inode, lblock, len, ~0,
+ EXTENT_STATUS_HOLE);
}
/*
@@ -4362,8 +4358,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
* put just found gap into cache to speed up
* subsequent requests
*/
- if ((flags & EXT4_GET_BLOCKS_NO_PUT_HOLE) == 0)
- ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
+ ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
goto out2;
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 367a60c..d1ad9f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1485,11 +1485,9 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
map->m_flags |= EXT4_MAP_FROM_CLUSTER;
retval = 0;
} else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
- retval = ext4_ext_map_blocks(NULL, inode, map,
- EXT4_GET_BLOCKS_NO_PUT_HOLE);
+ retval = ext4_ext_map_blocks(NULL, inode, map, 0);
else
- retval = ext4_ind_map_blocks(NULL, inode, map,
- EXT4_GET_BLOCKS_NO_PUT_HOLE);
+ retval = ext4_ind_map_blocks(NULL, inode, map, 0);
add_delayed:
if (retval == 0) {
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index ff4bd1b..9337d36 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -43,8 +43,7 @@ struct extent_status;
{ EXT4_GET_BLOCKS_METADATA_NOFAIL, "METADATA_NOFAIL" }, \
{ EXT4_GET_BLOCKS_NO_NORMALIZE, "NO_NORMALIZE" }, \
{ EXT4_GET_BLOCKS_KEEP_SIZE, "KEEP_SIZE" }, \
- { EXT4_GET_BLOCKS_NO_LOCK, "NO_LOCK" }, \
- { EXT4_GET_BLOCKS_NO_PUT_HOLE, "NO_PUT_HOLE" })
+ { EXT4_GET_BLOCKS_NO_LOCK, "NO_LOCK" })
#define show_mflags(flags) __print_flags(flags, "", \
{ EXT4_MAP_NEW, "N" }, \
--
1.7.9.7
--
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