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Date: Mon, 14 Nov 2011 11:07:06 +0800
From: Yongqiang Yang <xiaoqiangnk@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, Yongqiang Yang <xiaoqiangnk@...il.com>
Subject: [PATCH 2/2] ext4: let ext4 cache uninitialized extents
For now, ext4 does not cache uninitialized extents. Thus,
ext4_ext_map_blocks on a fallocated file lookups extent tree
every time. This patch tries to cache uninitialized extents.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
---
fs/ext4/ext4.h | 1 +
fs/ext4/extents.c | 52 +++++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 42 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 604c200..80d29ed 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -770,6 +770,7 @@ do { \
/*
* storage for cached extent
* If ec_len == 0, then the cache is invalid.
+ * If ec_len > EXT_INIT_MAX_LEN, then the cache is uninitialized.
* If ec_start == 0, then the cache represents a gap (null mapping)
*/
struct ext4_ext_cache {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a99d123..7d68186 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2009,6 +2009,18 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
ext4_ext_put_in_cache(inode, lblock, len, 0);
}
+static unsigned int ext4_ext_cache_get_actual_len(struct ext4_ext_cache *cex)
+{
+ return cex->ec_start == 0 ? cex->ec_len :
+ (cex->ec_len <= EXT_INIT_MAX_LEN ? cex->ec_len :
+ (cex->ec_len - EXT_INIT_MAX_LEN));
+}
+
+static int ext4_ext_cache_is_uninitialized(struct ext4_ext_cache *cex)
+{
+ return cex->ec_start == 0 ? 0 : cex->ec_len > EXT_INIT_MAX_LEN;
+}
+
/*
* ext4_ext_check_cache()
* Checks to see if the given block is in the cache.
@@ -2042,11 +2054,14 @@ static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
if (cex->ec_len == 0)
goto errout;
- if (in_range(block, cex->ec_block, cex->ec_len)) {
+ if (in_range(block, cex->ec_block,
+ ext4_ext_cache_get_actual_len(cex))) {
memcpy(ex, cex, sizeof(struct ext4_ext_cache));
- ext_debug("%u cached by %u:%u:%llu\n",
- block,
- cex->ec_block, cex->ec_len, cex->ec_start);
+ ext_debug("%u cached by %u:[%d]%u:%llu\n",
+ block, cex->ec_block,
+ ext4_ext_cache_is_uninitialized(cex),
+ ext4_ext_cache_get_actual_len(cex),
+ cex->ec_start);
ret = 1;
}
errout:
@@ -2061,6 +2076,7 @@ errout:
#define CACHE_EXTENT_HOLE 1
#define CACHE_EXTENT_INITIALIZED 2
+#define CACHE_EXTENT_UNINITIALIZED 3
/*
* ext4_ext_in_cache()
* Checks to see if the given block is in the cache.
@@ -2084,9 +2100,11 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
if (ext4_ext_check_cache(inode, block, &cex)) {
ex->ee_block = cpu_to_le32(cex.ec_block);
ext4_ext_store_pblock(ex, cex.ec_start);
- ex->ee_len = cpu_to_le16(cex.ec_len);
+ ex->ee_len = ext4_ext_cache_get_actual_len(&cex);
if (cex.ec_start == 0)
ret = CACHE_EXTENT_HOLE;
+ else if (ext4_ext_cache_is_uninitialized(&cex))
+ ret = CACHE_EXTENT_UNINITIALIZED;
else
ret = CACHE_EXTENT_INITIALIZED;
}
@@ -3483,6 +3501,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
if (ext4_should_dioread_nolock(inode))
map->m_flags |= EXT4_MAP_UNINIT;
+ ext4_ext_invalidate_cache(inode);
goto out;
}
/* IO end_io complete, convert the filled extent to written */
@@ -3493,6 +3512,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
ext4_update_inode_fsync_trans(handle, inode, 1);
err = check_eofblocks_fl(handle, inode, map->m_lblk,
path, map->m_len);
+ ext4_ext_invalidate_cache(inode);
} else
err = ret;
goto out2;
@@ -3514,14 +3534,21 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
* the buffer head will be unmapped so that
* a read from the block returns 0s.
*/
+ int depth = ext_depth(inode);
+ struct ext4_extent *ex = path[depth].p_ext;
+ ext4_ext_put_in_cache(inode, le32_to_cpu(ex->ee_block),
+ le16_to_cpu(ex->ee_len),
+ ext4_ext_pblock(ex));
map->m_flags |= EXT4_MAP_UNWRITTEN;
goto out1;
}
/* buffered write, writepage time, convert*/
ret = ext4_ext_convert_to_initialized(handle, inode, map, path);
- if (ret >= 0)
+ if (ret >= 0) {
ext4_update_inode_fsync_trans(handle, inode, 1);
+ ext4_ext_invalidate_cache(inode);
+ }
out:
if (ret <= 0) {
err = ret;
@@ -3744,6 +3771,12 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
/* we should allocate requested block */
break;
+ case CACHE_EXTENT_UNINITIALIZED:
+ if (flags & EXT4_GET_BLOCKS_CREATE)
+ break;
+
+ map->m_flags |= EXT4_MAP_UNWRITTEN;
+
case CACHE_EXTENT_INITIALIZED:
/* block is already allocated */
if (sbi->s_cluster_ratio > 1)
@@ -3808,10 +3841,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
ee_block, ee_len, newblock);
if ((flags & EXT4_GET_BLOCKS_PUNCH_OUT_EXT) == 0) {
- /*
- * Do not put uninitialized extent
- * in the cache
- */
if (!ext4_ext_is_uninitialized(ex)) {
ext4_ext_put_in_cache(inode, ee_block,
ee_len, ee_start);
@@ -4165,7 +4194,8 @@ out:
if (allocated > map->m_len)
allocated = map->m_len;
ext4_ext_show_leaf(inode, path);
- map->m_flags |= EXT4_MAP_MAPPED;
+ if (!(map->m_flags&EXT4_MAP_UNWRITTEN))
+ map->m_flags |= EXT4_MAP_MAPPED;
map->m_pblk = newblock;
map->m_len = allocated;
out2:
--
1.7.5.1
--
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