From b05e6ae58a13b56e3e11882c1fc71948c9b29760 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 10 Jan 2011 12:13:26 -0500 Subject: 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" --- fs/ext4/ext4.h | 3 ++- fs/ext4/ext4_extents.h | 6 +----- fs/ext4/extents.c | 37 +++++++++++++++---------------------- 3 files changed, 18 insertions(+), 28 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 746a59853a07..de937fc10503 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -738,12 +738,13 @@ do { \ /* * storage for cached extent + * If ec_len == 0, then the cache is invalid. + * If ec_start == 0, then the cache represents a gap (null mapping) */ struct ext4_ext_cache { ext4_fsblk_t ec_start; ext4_lblk_t ec_block; __u32 ec_len; /* must be 32bit to return holes */ - __u32 ec_type; }; /* diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h index dfdda1766927..2e29abb30f76 100644 --- a/fs/ext4/ext4_extents.h +++ b/fs/ext4/ext4_extents.h @@ -119,10 +119,6 @@ struct ext4_ext_path { * structure for external API */ -#define EXT4_EXT_CACHE_NO 0 -#define EXT4_EXT_CACHE_GAP 1 -#define EXT4_EXT_CACHE_EXTENT 2 - /* * to be called by ext4_ext_walk_space() * negative retcode - error @@ -197,7 +193,7 @@ static inline unsigned short ext_depth(struct inode *inode) static inline void ext4_ext_invalidate_cache(struct inode *inode) { - EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO; + EXT4_I(inode)->i_cached_extent.ec_len = 0; } static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index f1a4354ea3cf..9081d1060a5f 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1894,12 +1894,10 @@ static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block, cbex.ec_block = start; cbex.ec_len = end - start; cbex.ec_start = 0; - cbex.ec_type = EXT4_EXT_CACHE_GAP; } else { cbex.ec_block = le32_to_cpu(ex->ee_block); cbex.ec_len = ext4_ext_get_actual_len(ex); cbex.ec_start = ext4_ext_pblock(ex); - cbex.ec_type = EXT4_EXT_CACHE_EXTENT; } if (unlikely(cbex.ec_len == 0)) { @@ -1939,13 +1937,12 @@ static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block, static void ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block, - __u32 len, ext4_fsblk_t start, int type) + __u32 len, ext4_fsblk_t start) { struct ext4_ext_cache *cex; BUG_ON(len == 0); spin_lock(&EXT4_I(inode)->i_block_reservation_lock); cex = &EXT4_I(inode)->i_cached_extent; - cex->ec_type = type; cex->ec_block = block; cex->ec_len = len; cex->ec_start = start; @@ -1998,15 +1995,18 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path, } ext_debug(" -> %u:%lu\n", lblock, len); - ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP); + ext4_ext_put_in_cache(inode, lblock, len, 0); } +/* + * Return 0 if cache is invalid; 1 if the cache is valid + */ static int ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, struct ext4_extent *ex) { struct ext4_ext_cache *cex; - int ret = EXT4_EXT_CACHE_NO; + int ret = 0; /* * We borrow i_block_reservation_lock to protect i_cached_extent @@ -2015,11 +2015,9 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, cex = &EXT4_I(inode)->i_cached_extent; /* has cache valid data? */ - if (cex->ec_type == EXT4_EXT_CACHE_NO) + if (cex->ec_len == 0) goto errout; - BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP && - cex->ec_type != EXT4_EXT_CACHE_EXTENT); if (in_range(block, cex->ec_block, cex->ec_len)) { ex->ee_block = cpu_to_le32(cex->ec_block); ext4_ext_store_pblock(ex, cex->ec_start); @@ -2027,7 +2025,7 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, ext_debug("%u cached by %u:%u:%llu\n", block, cex->ec_block, cex->ec_len, cex->ec_start); - ret = cex->ec_type; + ret = 1; } errout: spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); @@ -3298,7 +3296,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, struct ext4_extent_header *eh; struct ext4_extent newex, *ex; ext4_fsblk_t newblock; - int err = 0, depth, ret, cache_type; + int err = 0, depth, ret; unsigned int allocated = 0; struct ext4_allocation_request ar; ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio; @@ -3307,9 +3305,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, map->m_lblk, map->m_len, inode->i_ino); /* check in cache */ - cache_type = ext4_ext_in_cache(inode, map->m_lblk, &newex); - if (cache_type) { - if (cache_type == EXT4_EXT_CACHE_GAP) { + if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) { + if (!newex.ee_start_lo && !newex.ee_start_hi) { if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) { /* * block isn't allocated yet and @@ -3318,7 +3315,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, goto out2; } /* we should allocate requested block */ - } else if (cache_type == EXT4_EXT_CACHE_EXTENT) { + } else { /* block is already allocated */ newblock = map->m_lblk - le32_to_cpu(newex.ee_block) @@ -3327,8 +3324,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, allocated = ext4_ext_get_actual_len(&newex) - (map->m_lblk - le32_to_cpu(newex.ee_block)); goto out; - } else { - BUG(); } } @@ -3379,8 +3374,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, /* 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, - EXT4_EXT_CACHE_EXTENT); + ee_len, ee_start); goto out; } ret = ext4_ext_handle_uninitialized_extents(handle, @@ -3512,8 +3506,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, * when it is _not_ an uninitialized extent. */ if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) { - ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock, - EXT4_EXT_CACHE_EXTENT); + ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock); ext4_update_inode_fsync_trans(handle, inode, 1); } else ext4_update_inode_fsync_trans(handle, inode, 0); @@ -3789,7 +3782,7 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path, logical = (__u64)newex->ec_block << blksize_bits; - if (newex->ec_type == EXT4_EXT_CACHE_GAP) { + if (newex->ec_start == 0) { pgoff_t offset; struct page *page; struct buffer_head *bh = NULL; -- cgit v1.2.3