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Commit b05e6ae58a13b56e3e11882c1fc71948c9b29760

Authored by Theodore Ts'o
1 parent 01f49d0b9d
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

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>

Showing 3 changed files with 18 additions and 28 deletions Side-by-side Diff

... ... @@ -738,12 +738,13 @@
738 738  
739 739 /*
740 740 * storage for cached extent
  741 + * If ec_len == 0, then the cache is invalid.
  742 + * If ec_start == 0, then the cache represents a gap (null mapping)
741 743 */
742 744 struct ext4_ext_cache {
743 745 ext4_fsblk_t ec_start;
744 746 ext4_lblk_t ec_block;
745 747 __u32 ec_len; /* must be 32bit to return holes */
746   - __u32 ec_type;
747 748 };
748 749  
749 750 /*
fs/ext4/ext4_extents.h
Diff comments   View file @ b05e6ae
... ... @@ -119,10 +119,6 @@
119 119 * structure for external API
120 120 */
121 121  
122   -#define EXT4_EXT_CACHE_NO 0
123   -#define EXT4_EXT_CACHE_GAP 1
124   -#define EXT4_EXT_CACHE_EXTENT 2
125   -
126 122 /*
127 123 * to be called by ext4_ext_walk_space()
128 124 * negative retcode - error
... ... @@ -197,7 +193,7 @@
197 193 static inline void
198 194 ext4_ext_invalidate_cache(struct inode *inode)
199 195 {
200   - EXT4_I(inode)->i_cached_extent.ec_type = EXT4_EXT_CACHE_NO;
  196 + EXT4_I(inode)->i_cached_extent.ec_len = 0;
201 197 }
202 198  
203 199 static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
... ... @@ -1894,12 +1894,10 @@
1894 1894 cbex.ec_block = start;
1895 1895 cbex.ec_len = end - start;
1896 1896 cbex.ec_start = 0;
1897   - cbex.ec_type = EXT4_EXT_CACHE_GAP;
1898 1897 } else {
1899 1898 cbex.ec_block = le32_to_cpu(ex->ee_block);
1900 1899 cbex.ec_len = ext4_ext_get_actual_len(ex);
1901 1900 cbex.ec_start = ext4_ext_pblock(ex);
1902   - cbex.ec_type = EXT4_EXT_CACHE_EXTENT;
1903 1901 }
1904 1902  
1905 1903 if (unlikely(cbex.ec_len == 0)) {
1906 1904  
... ... @@ -1939,13 +1937,12 @@
1939 1937  
1940 1938 static void
1941 1939 ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
1942   - __u32 len, ext4_fsblk_t start, int type)
  1940 + __u32 len, ext4_fsblk_t start)
1943 1941 {
1944 1942 struct ext4_ext_cache *cex;
1945 1943 BUG_ON(len == 0);
1946 1944 spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1947 1945 cex = &EXT4_I(inode)->i_cached_extent;
1948   - cex->ec_type = type;
1949 1946 cex->ec_block = block;
1950 1947 cex->ec_len = len;
1951 1948 cex->ec_start = start;
1952 1949  
1953 1950  
... ... @@ -1998,15 +1995,18 @@
1998 1995 }
1999 1996  
2000 1997 ext_debug(" -> %u:%lu\n", lblock, len);
2001   - ext4_ext_put_in_cache(inode, lblock, len, 0, EXT4_EXT_CACHE_GAP);
  1998 + ext4_ext_put_in_cache(inode, lblock, len, 0);
2002 1999 }
2003 2000  
  2001 +/*
  2002 + * Return 0 if cache is invalid; 1 if the cache is valid
  2003 + */
2004 2004 static int
2005 2005 ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
2006 2006 struct ext4_extent *ex)
2007 2007 {
2008 2008 struct ext4_ext_cache *cex;
2009   - int ret = EXT4_EXT_CACHE_NO;
  2009 + int ret = 0;
2010 2010  
2011 2011 /*
2012 2012 * We borrow i_block_reservation_lock to protect i_cached_extent
2013 2013  
... ... @@ -2015,11 +2015,9 @@
2015 2015 cex = &EXT4_I(inode)->i_cached_extent;
2016 2016  
2017 2017 /* has cache valid data? */
2018   - if (cex->ec_type == EXT4_EXT_CACHE_NO)
  2018 + if (cex->ec_len == 0)
2019 2019 goto errout;
2020 2020  
2021   - BUG_ON(cex->ec_type != EXT4_EXT_CACHE_GAP &&
2022   - cex->ec_type != EXT4_EXT_CACHE_EXTENT);
2023 2021 if (in_range(block, cex->ec_block, cex->ec_len)) {
2024 2022 ex->ee_block = cpu_to_le32(cex->ec_block);
2025 2023 ext4_ext_store_pblock(ex, cex->ec_start);
... ... @@ -2027,7 +2025,7 @@
2027 2025 ext_debug("%u cached by %u:%u:%llu\n",
2028 2026 block,
2029 2027 cex->ec_block, cex->ec_len, cex->ec_start);
2030   - ret = cex->ec_type;
  2028 + ret = 1;
2031 2029 }
2032 2030 errout:
2033 2031 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
... ... @@ -3298,7 +3296,7 @@
3298 3296 struct ext4_extent_header *eh;
3299 3297 struct ext4_extent newex, *ex;
3300 3298 ext4_fsblk_t newblock;
3301   - int err = 0, depth, ret, cache_type;
  3299 + int err = 0, depth, ret;
3302 3300 unsigned int allocated = 0;
3303 3301 struct ext4_allocation_request ar;
3304 3302 ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
... ... @@ -3307,9 +3305,8 @@
3307 3305 map->m_lblk, map->m_len, inode->i_ino);
3308 3306  
3309 3307 /* check in cache */
3310   - cache_type = ext4_ext_in_cache(inode, map->m_lblk, &newex);
3311   - if (cache_type) {
3312   - if (cache_type == EXT4_EXT_CACHE_GAP) {
  3308 + if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
  3309 + if (!newex.ee_start_lo && !newex.ee_start_hi) {
3313 3310 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
3314 3311 /*
3315 3312 * block isn't allocated yet and
... ... @@ -3318,7 +3315,7 @@
3318 3315 goto out2;
3319 3316 }
3320 3317 /* we should allocate requested block */
3321   - } else if (cache_type == EXT4_EXT_CACHE_EXTENT) {
  3318 + } else {
3322 3319 /* block is already allocated */
3323 3320 newblock = map->m_lblk
3324 3321 - le32_to_cpu(newex.ee_block)
... ... @@ -3327,8 +3324,6 @@
3327 3324 allocated = ext4_ext_get_actual_len(&newex) -
3328 3325 (map->m_lblk - le32_to_cpu(newex.ee_block));
3329 3326 goto out;
3330   - } else {
3331   - BUG();
3332 3327 }
3333 3328 }
3334 3329  
... ... @@ -3379,8 +3374,7 @@
3379 3374 /* Do not put uninitialized extent in the cache */
3380 3375 if (!ext4_ext_is_uninitialized(ex)) {
3381 3376 ext4_ext_put_in_cache(inode, ee_block,
3382   - ee_len, ee_start,
3383   - EXT4_EXT_CACHE_EXTENT);
  3377 + ee_len, ee_start);
3384 3378 goto out;
3385 3379 }
3386 3380 ret = ext4_ext_handle_uninitialized_extents(handle,
... ... @@ -3512,8 +3506,7 @@
3512 3506 * when it is _not_ an uninitialized extent.
3513 3507 */
3514 3508 if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
3515   - ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock,
3516   - EXT4_EXT_CACHE_EXTENT);
  3509 + ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock);
3517 3510 ext4_update_inode_fsync_trans(handle, inode, 1);
3518 3511 } else
3519 3512 ext4_update_inode_fsync_trans(handle, inode, 0);
... ... @@ -3789,7 +3782,7 @@
3789 3782  
3790 3783 logical = (__u64)newex->ec_block << blksize_bits;
3791 3784  
3792   - if (newex->ec_type == EXT4_EXT_CACHE_GAP) {
  3785 + if (newex->ec_start == 0) {
3793 3786 pgoff_t offset;
3794 3787 struct page *page;
3795 3788 struct buffer_head *bh = NULL;