mirror of https://gitee.com/openkylin/linux.git
ext4: drop ec_type from the ext4_ext_cache structure
We can encode the ec_type information by using ee_len == 0 to denote EXT4_EXT_CACHE_NO, ee_start == 0 to denote EXT4_EXT_CACHE_GAP, and if neither is true, then the cache type must be EXT4_EXT_CACHE_EXTENT. This allows us to reduce the size of ext4_ext_inode by another 8 bytes. (ec_type is 4 bytes, plus another 4 bytes of padding) Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
parent
01f49d0b9d
commit
b05e6ae58a
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@ -738,12 +738,13 @@ do { \
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/*
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* storage for cached extent
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* If ec_len == 0, then the cache is invalid.
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* If ec_start == 0, then the cache represents a gap (null mapping)
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*/
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struct ext4_ext_cache {
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ext4_fsblk_t ec_start;
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ext4_lblk_t ec_block;
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__u32 ec_len; /* must be 32bit to return holes */
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__u32 ec_type;
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};
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/*
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@ -119,10 +119,6 @@ struct ext4_ext_path {
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* structure for external API
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*/
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#define EXT4_EXT_CACHE_NO 0
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#define EXT4_EXT_CACHE_GAP 1
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#define EXT4_EXT_CACHE_EXTENT 2
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/*
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* to be called by ext4_ext_walk_space()
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* negative retcode - error
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@ -197,7 +193,7 @@ static inline unsigned short ext_depth(struct inode *inode)
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static inline void
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ext4_ext_invalidate_cache(struct inode *inode)
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{
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EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
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EXT4_I(inode)->i_cached_extent.ec_len = 0;
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}
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static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
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@ -1894,12 +1894,10 @@ static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block,
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cbex.ec_block = start;
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cbex.ec_len = end - start;
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cbex.ec_start = 0;
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cbex.ec_type = EXT4_EXT_CACHE_GAP;
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} else {
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cbex.ec_block = le32_to_cpu(ex->ee_block);
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cbex.ec_len = ext4_ext_get_actual_len(ex);
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cbex.ec_start = ext4_ext_pblock(ex);
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cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
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}
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if (unlikely(cbex.ec_len == 0)) {
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@ -1939,13 +1937,12 @@ static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block,
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static void
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ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
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__u32 len, ext4_fsblk_t start, int type)
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__u32 len, ext4_fsblk_t start)
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{
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struct ext4_ext_cache *cex;
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BUG_ON(len == 0);
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spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
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cex = &EXT4_I(inode)->i_cached_extent;
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cex->ec_type = type;
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cex->ec_block = block;
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cex->ec_len = len;
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cex->ec_start = start;
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@ -1998,15 +1995,18 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
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}
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ext_debug(" -> %u:%lu\n", lblock, len);
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ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP);
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ext4_ext_put_in_cache(inode, lblock, len, 0);
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}
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/*
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* Return 0 if cache is invalid; 1 if the cache is valid
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*/
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static int
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ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
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struct ext4_extent *ex)
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{
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struct ext4_ext_cache *cex;
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int ret = EXT4_EXT_CACHE_NO;
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int ret = 0;
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/*
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* We borrow i_block_reservation_lock to protect i_cached_extent
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@ -2015,11 +2015,9 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
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cex = &EXT4_I(inode)->i_cached_extent;
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/* has cache valid data? */
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if (cex->ec_type == EXT4_EXT_CACHE_NO)
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if (cex->ec_len == 0)
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goto errout;
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BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
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cex->ec_type != EXT4_EXT_CACHE_EXTENT);
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if (in_range(block, cex->ec_block, cex->ec_len)) {
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ex->ee_block = cpu_to_le32(cex->ec_block);
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ext4_ext_store_pblock(ex, cex->ec_start);
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@ -2027,7 +2025,7 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
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ext_debug("%u cached by %u:%u:%llu\n",
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block,
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cex->ec_block, cex->ec_len, cex->ec_start);
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ret = cex->ec_type;
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ret = 1;
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}
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errout:
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spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
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@ -3298,7 +3296,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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struct ext4_extent_header *eh;
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struct ext4_extent newex, *ex;
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ext4_fsblk_t newblock;
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int err = 0, depth, ret, cache_type;
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int err = 0, depth, ret;
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unsigned int allocated = 0;
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struct ext4_allocation_request ar;
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ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
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@ -3307,9 +3305,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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map->m_lblk, map->m_len, inode->i_ino);
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/* check in cache */
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cache_type = ext4_ext_in_cache(inode, map->m_lblk, &newex);
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if (cache_type) {
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if (cache_type == EXT4_EXT_CACHE_GAP) {
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if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
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if (!newex.ee_start_lo && !newex.ee_start_hi) {
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if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
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/*
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* block isn't allocated yet and
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@ -3318,7 +3315,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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goto out2;
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}
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/* we should allocate requested block */
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} else if (cache_type == EXT4_EXT_CACHE_EXTENT) {
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} else {
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/* block is already allocated */
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newblock = map->m_lblk
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- le32_to_cpu(newex.ee_block)
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@ -3327,8 +3324,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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allocated = ext4_ext_get_actual_len(&newex) -
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(map->m_lblk - le32_to_cpu(newex.ee_block));
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goto out;
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} else {
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BUG();
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}
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}
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@ -3379,8 +3374,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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/* Do not put uninitialized extent in the cache */
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if (!ext4_ext_is_uninitialized(ex)) {
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ext4_ext_put_in_cache(inode, ee_block,
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ee_len, ee_start,
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EXT4_EXT_CACHE_EXTENT);
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ee_len, ee_start);
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goto out;
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}
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ret = ext4_ext_handle_uninitialized_extents(handle,
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@ -3512,8 +3506,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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* when it is _not_ an uninitialized extent.
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*/
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if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
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ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock,
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EXT4_EXT_CACHE_EXTENT);
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ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock);
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ext4_update_inode_fsync_trans(handle, inode, 1);
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} else
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ext4_update_inode_fsync_trans(handle, inode, 0);
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@ -3789,7 +3782,7 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
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logical = (__u64)newex->ec_block << blksize_bits;
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if (newex->ec_type == EXT4_EXT_CACHE_GAP) {
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if (newex->ec_start == 0) {
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pgoff_t offset;
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struct page *page;
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struct buffer_head *bh = NULL;
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