ext4: remove single extent cache

Single extent cache could be removed because we have extent status tree
as a extent cache, and it would be better.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jan kara <jack@suse.cz>

1 files changed, 38 insertions, 141 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b9d7a2363736..372b2cbee07e 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -112,7 +112,7 @@ static int ext4_split_extent_at(handle_t *handle,
                              int flags);
 
 static int ext4_find_delayed_extent(struct inode *inode,
-                                    struct ext4_ext_cache *newex);
+                                    struct extent_status *newes);
 
 static int ext4_ext_truncate_extend_restart(handle_t *handle,
                                             struct inode *inode,
@@ -714,7 +714,6 @@ int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
         eh->eh_magic = EXT4_EXT_MAGIC;
         eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
         ext4_mark_inode_dirty(handle, inode);
-        ext4_ext_invalidate_cache(inode);
         return 0;
 }
 
@@ -1963,7 +1962,6 @@ cleanup:
                 ext4_ext_drop_refs(npath);
                 kfree(npath);
         }
-        ext4_ext_invalidate_cache(inode);
         return err;
 }
 
@@ -1972,8 +1970,8 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
                                     struct fiemap_extent_info *fieinfo)
 {
         struct ext4_ext_path *path = NULL;
-        struct ext4_ext_cache newex;
         struct ext4_extent *ex;
+        struct extent_status es;
         ext4_lblk_t next, next_del, start = 0, end = 0;
         ext4_lblk_t last = block + num;
         int exists, depth = 0, err = 0;
@@ -2047,31 +2045,31 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
                 BUG_ON(end <= start);
 
                 if (!exists) {
-                        newex.ec_block = start;
-                        newex.ec_len = end - start;
-                        newex.ec_start = 0;
+                        es.es_lblk = start;
+                        es.es_len = end - start;
+                        es.es_pblk = 0;
                 } else {
-                        newex.ec_block = le32_to_cpu(ex->ee_block);
-                        newex.ec_len = ext4_ext_get_actual_len(ex);
-                        newex.ec_start = ext4_ext_pblock(ex);
+                        es.es_lblk = le32_to_cpu(ex->ee_block);
+                        es.es_len = ext4_ext_get_actual_len(ex);
+                        es.es_pblk = ext4_ext_pblock(ex);
                         if (ext4_ext_is_uninitialized(ex))
                                 flags |= FIEMAP_EXTENT_UNWRITTEN;
                 }
 
                 /*
-                 * Find delayed extent and update newex accordingly. We call
-                 * it even in !exists case to find out whether newex is the
+                 * Find delayed extent and update es accordingly. We call
+                 * it even in !exists case to find out whether es is the
                  * last existing extent or not.
                  */
-                next_del = ext4_find_delayed_extent(inode, &newex);
+                next_del = ext4_find_delayed_extent(inode, &es);
                 if (!exists && next_del) {
                         exists = 1;
                         flags |= FIEMAP_EXTENT_DELALLOC;
                 }
                 up_read(&EXT4_I(inode)->i_data_sem);
 
-                if (unlikely(newex.ec_len == 0)) {
-                        EXT4_ERROR_INODE(inode, "newex.ec_len == 0");
+                if (unlikely(es.es_len == 0)) {
+                        EXT4_ERROR_INODE(inode, "es.es_len == 0");
                         err = -EIO;
                         break;
                 }
@@ -2102,9 +2100,9 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
 
                 if (exists) {
                         err = fiemap_fill_next_extent(fieinfo,
-                                (__u64)newex.ec_block << blksize_bits,
-                                (__u64)newex.ec_start << blksize_bits,
-                                (__u64)newex.ec_len << blksize_bits,
+                                (__u64)es.es_lblk << blksize_bits,
+                                (__u64)es.es_pblk << blksize_bits,
+                                (__u64)es.es_len << blksize_bits,
                                 flags);
                         if (err < 0)
                                 break;
@@ -2114,7 +2112,7 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
                         }
                 }
 
-                block = newex.ec_block + newex.ec_len;
+                block = es.es_lblk + es.es_len;
         }
 
         if (path) {
@@ -2125,21 +2123,6 @@ static int ext4_fill_fiemap_extents(struct inode *inode,
         return err;
 }
 
-static void
-ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
-                        __u32 len, ext4_fsblk_t start)
-{
-        struct ext4_ext_cache *cex;
-        BUG_ON(len == 0);
-        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-        trace_ext4_ext_put_in_cache(inode, block, len, start);
-        cex = &EXT4_I(inode)->i_cached_extent;
-        cex->ec_block = block;
-        cex->ec_len = len;
-        cex->ec_start = start;
-        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
-}
-
 /*
  * ext4_ext_put_gap_in_cache:
  * calculate boundaries of the gap that the requested block fits into
@@ -2156,9 +2139,10 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
 
         ex = path[depth].p_ext;
         if (ex == NULL) {
-                /* there is no extent yet, so gap is [0;-] */
-                lblock = 0;
-                len = EXT_MAX_BLOCKS;
+                /*
+                 * there is no extent yet, so gap is [0;-] and we
+                 * don't cache it
+                 */
                 ext_debug("cache gap(whole file):");
         } else if (block < le32_to_cpu(ex->ee_block)) {
                 lblock = block;
@@ -2192,52 +2176,6 @@ 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_in_cache()
- * Checks to see if the given block is in the cache.
- * If it is, the cached extent is stored in the given
- * cache extent pointer.
- *
- * @inode: The files inode
- * @block: The block to look for in the cache
- * @ex:    Pointer where the cached extent will be stored
- *         if it contains block
- *
- * 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 = 0;
-
-        /*
-         * We borrow i_block_reservation_lock to protect i_cached_extent
-         */
-        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
-        cex = &EXT4_I(inode)->i_cached_extent;
-
-        /* has cache valid data? */
-        if (cex->ec_len == 0)
-                goto errout;
-
-        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);
-                ex->ee_len = cpu_to_le16(cex->ec_len);
-                ext_debug("%u cached by %u:%u:%llu\n",
-                                block,
-                                cex->ec_block, cex->ec_len, cex->ec_start);
-                ret = 1;
-        }
-errout:
-        trace_ext4_ext_in_cache(inode, block, ret);
-        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
-        return ret;
 }
 
 /*
@@ -2677,8 +2615,6 @@ static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
                 return PTR_ERR(handle);
 
 again:
-        ext4_ext_invalidate_cache(inode);
-
         trace_ext4_ext_remove_space(inode, start, depth);
 
         /*
@@ -3920,35 +3856,6 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
                   map->m_lblk, map->m_len, inode->i_ino);
         trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
 
-        /* check in cache */
-        if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
-                if (!newex.ee_start_lo && !newex.ee_start_hi) {
-                        if ((sbi->s_cluster_ratio > 1) &&
-                            ext4_find_delalloc_cluster(inode, map->m_lblk))
-                                map->m_flags |= EXT4_MAP_FROM_CLUSTER;
-
-                        if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
-                                /*
-                                 * block isn't allocated yet and
-                                 * user doesn't want to allocate it
-                                 */
-                                goto out2;
-                        }
-                        /* we should allocate requested block */
-                } else {
-                        /* block is already allocated */
-                        if (sbi->s_cluster_ratio > 1)
-                                map->m_flags |= EXT4_MAP_FROM_CLUSTER;
-                        newblock = map->m_lblk
-                                   - le32_to_cpu(newex.ee_block)
-                                   + ext4_ext_pblock(&newex);
-                        /* number of remaining blocks in the extent */
-                        allocated = ext4_ext_get_actual_len(&newex) -
-                                (map->m_lblk - le32_to_cpu(newex.ee_block));
-                        goto out;
-                }
-        }
-
         /* find extent for this block */
         path = ext4_ext_find_extent(inode, map->m_lblk, NULL);
         if (IS_ERR(path)) {
@@ -3995,15 +3902,9 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
                         ext_debug("%u fit into %u:%d -> %llu\n", map->m_lblk,
                                   ee_block, ee_len, newblock);
 
-                        /*
-                         * 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);
+                        if (!ext4_ext_is_uninitialized(ex))
                                 goto out;
-                        }
+
                         allocated = ext4_ext_handle_uninitialized_extents(
                                 handle, inode, map, path, flags,
                                 allocated, newblock);
@@ -4265,10 +4166,9 @@ got_allocated_blocks:
          * Cache the extent and update transaction to commit on fdatasync only
          * 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);
+        if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0)
                 ext4_update_inode_fsync_trans(handle, inode, 1);
-        } else
+        else
                 ext4_update_inode_fsync_trans(handle, inode, 0);
 out:
         if (allocated > map->m_len)
@@ -4327,7 +4227,6 @@ void ext4_ext_truncate(struct inode *inode)
                 goto out_stop;
 
         down_write(&EXT4_I(inode)->i_data_sem);
-        ext4_ext_invalidate_cache(inode);
 
         ext4_discard_preallocations(inode);
 
@@ -4576,42 +4475,42 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
 }
 
 /*
- * If newex is not existing extent (newex->ec_start equals zero) find
- * delayed extent at start of newex and update newex accordingly and
+ * If newes is not existing extent (newes->ec_pblk equals zero) find
+ * delayed extent at start of newes and update newes accordingly and
  * return start of the next delayed extent.
  *
- * If newex is existing extent (newex->ec_start is not equal zero)
+ * If newes is existing extent (newes->ec_pblk is not equal zero)
  * return start of next delayed extent or EXT_MAX_BLOCKS if no delayed
- * extent found. Leave newex unmodified.
+ * extent found. Leave newes unmodified.
  */
 static int ext4_find_delayed_extent(struct inode *inode,
-                                    struct ext4_ext_cache *newex)
+                                    struct extent_status *newes)
 {
         struct extent_status es;
         ext4_lblk_t block, next_del;
 
-        ext4_es_find_delayed_extent(inode, newex->ec_block, &es);
+        ext4_es_find_delayed_extent(inode, newes->es_lblk, &es);
 
-        if (newex->ec_start == 0) {
+        if (newes->es_pblk == 0) {
                 /*
-                 * No extent in extent-tree contains block @newex->ec_start,
+                 * No extent in extent-tree contains block @newes->es_pblk,
                  * then the block may stay in 1)a hole or 2)delayed-extent.
                  */
                 if (es.es_len == 0)
                         /* A hole found. */
                         return 0;
 
-                if (es.es_lblk > newex->ec_block) {
+                if (es.es_lblk > newes->es_lblk) {
                         /* A hole found. */
-                        newex->ec_len = min(es.es_lblk - newex->ec_block,
-                                            newex->ec_len);
+                        newes->es_len = min(es.es_lblk - newes->es_lblk,
+                                            newes->es_len);
                         return 0;
                 }
 
-                newex->ec_len = es.es_lblk + es.es_len - newex->ec_block;
+                newes->es_len = es.es_lblk + es.es_len - newes->es_lblk;
         }
 
-        block = newex->ec_block + newex->ec_len;
+        block = newes->es_lblk + newes->es_len;
         ext4_es_find_delayed_extent(inode, block, &es);
         if (es.es_len == 0)
                 next_del = EXT_MAX_BLOCKS;
@@ -4815,14 +4714,12 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
                 goto out;
 
         down_write(&EXT4_I(inode)->i_data_sem);
-        ext4_ext_invalidate_cache(inode);
         ext4_discard_preallocations(inode);
 
         err = ext4_es_remove_extent(inode, first_block,
                                     stop_block - first_block);
         err = ext4_ext_remove_space(inode, first_block, stop_block - 1);
 
-        ext4_ext_invalidate_cache(inode);
         ext4_discard_preallocations(inode);
 
         if (IS_SYNC(inode))