diff options
Diffstat (limited to 'fs/ext4/extents.c')
| -rw-r--r-- | fs/ext4/extents.c | 226 |
1 files changed, 128 insertions, 98 deletions
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 3252606..e06e937 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -44,7 +44,10 @@ #include <asm/uaccess.h> -/* this macro combines low and hi parts of phys. blocknr into ext4_fsblk_t */ +/* + * ext_pblock: + * combine low and high parts of physical block number into ext4_fsblk_t + */ static inline ext4_fsblk_t ext_pblock(struct ext4_extent *ex) { ext4_fsblk_t block; @@ -55,7 +58,10 @@ static inline ext4_fsblk_t ext_pblock(struct ext4_extent *ex) return block; } -/* this macro combines low and hi parts of phys. blocknr into ext4_fsblk_t */ +/* + * idx_pblock: + * combine low and high parts of a leaf physical block number into ext4_fsblk_t + */ static inline ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix) { ext4_fsblk_t block; @@ -66,7 +72,11 @@ static inline ext4_fsblk_t idx_pblock(struct ext4_extent_idx *ix) return block; } -/* the routine stores large phys. blocknr into extent breaking it into parts */ +/* + * ext4_ext_store_pblock: + * stores a large physical block number into an extent struct, + * breaking it into parts + */ static inline void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb) { ex->ee_start = cpu_to_le32((unsigned long) (pb & 0xffffffff)); @@ -74,7 +84,11 @@ static inline void ext4_ext_store_pblock(struct ext4_extent *ex, ext4_fsblk_t pb ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) & 0xffff); } -/* the routine stores large phys. blocknr into index breaking it into parts */ +/* + * ext4_idx_store_pblock: + * stores a large physical block number into an index struct, + * breaking it into parts + */ static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix, ext4_fsblk_t pb) { ix->ei_leaf = cpu_to_le32((unsigned long) (pb & 0xffffffff)); @@ -179,8 +193,8 @@ static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode, if ((ex = path[depth].p_ext)) return ext_pblock(ex)+(block-le32_to_cpu(ex->ee_block)); - /* it looks index is empty - * try to find starting from index itself */ + /* it looks like index is empty; + * try to find starting block from index itself */ if (path[depth].p_bh) return path[depth].p_bh->b_blocknr; } @@ -317,7 +331,8 @@ static void ext4_ext_drop_refs(struct ext4_ext_path *path) } /* - * binary search for closest index by given block + * ext4_ext_binsearch_idx: + * binary search for the closest index of the given block */ static void ext4_ext_binsearch_idx(struct inode *inode, struct ext4_ext_path *path, int block) @@ -375,7 +390,8 @@ ext4_ext_binsearch_idx(struct inode *inode, struct ext4_ext_path *path, int bloc } /* - * binary search for closest extent by given block + * ext4_ext_binsearch: + * binary search for closest extent of the given block */ static void ext4_ext_binsearch(struct inode *inode, struct ext4_ext_path *path, int block) @@ -388,8 +404,8 @@ ext4_ext_binsearch(struct inode *inode, struct ext4_ext_path *path, int block) if (eh->eh_entries == 0) { /* - * this leaf is empty yet: - * we get such a leaf in split/add case + * this leaf is empty: + * we get such a leaf in split/add case */ return; } @@ -520,8 +536,9 @@ err: } /* - * insert new index [logical;ptr] into the block at cupr - * it check where to insert: before curp or after curp + * ext4_ext_insert_index: + * insert new index [@logical;@ptr] into the block at @curp; + * check where to insert: before @curp or after @curp */ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode, struct ext4_ext_path *curp, @@ -574,13 +591,14 @@ static int ext4_ext_insert_index(handle_t *handle, struct inode *inode, } /* - * routine inserts new subtree into the path, using free index entry - * at depth 'at: - * - allocates all needed blocks (new leaf and all intermediate index blocks) - * - makes decision where to split - * - moves remaining extens and index entries (right to the split point) - * into the newly allocated blocks - * - initialize subtree + * ext4_ext_split: + * inserts new subtree into the path, using free index entry + * at depth @at: + * - allocates all needed blocks (new leaf and all intermediate index blocks) + * - makes decision where to split + * - moves remaining extents and index entries (right to the split point) + * into the newly allocated blocks + * - initializes subtree */ static int ext4_ext_split(handle_t *handle, struct inode *inode, struct ext4_ext_path *path, @@ -598,14 +616,14 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, int err = 0; /* make decision: where to split? */ - /* FIXME: now desicion is simplest: at current extent */ + /* FIXME: now decision is simplest: at current extent */ - /* if current leaf will be splitted, then we should use + /* if current leaf will be split, then we should use * border from split point */ BUG_ON(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr)); if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) { border = path[depth].p_ext[1].ee_block; - ext_debug("leaf will be splitted." + ext_debug("leaf will be split." " next leaf starts at %d\n", le32_to_cpu(border)); } else { @@ -616,16 +634,16 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, } /* - * if error occurs, then we break processing - * and turn filesystem read-only. so, index won't + * If error occurs, then we break processing + * and mark filesystem read-only. index won't * be inserted and tree will be in consistent - * state. next mount will repair buffers too + * state. Next mount will repair buffers too. */ /* - * get array to track all allocated blocks - * we need this to handle errors and free blocks - * upon them + * Get array to track all allocated blocks. + * We need this to handle errors and free blocks + * upon them. */ ablocks = kmalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS); if (!ablocks) @@ -661,7 +679,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, neh->eh_depth = 0; ex = EXT_FIRST_EXTENT(neh); - /* move remain of path[depth] to the new leaf */ + /* move remainder of path[depth] to the new leaf */ BUG_ON(path[depth].p_hdr->eh_entries != path[depth].p_hdr->eh_max); /* start copy from next extent */ /* TODO: we could do it by single memmove */ @@ -813,11 +831,12 @@ cleanup: } /* - * routine implements tree growing procedure: - * - allocates new block - * - moves top-level data (index block or leaf) into the new block - * - initialize new top-level, creating index that points to the - * just created block + * ext4_ext_grow_indepth: + * implements tree growing procedure: + * - allocates new block + * - moves top-level data (index block or leaf) into the new block + * - initializes new top-level, creating index that points to the + * just created block */ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode, struct ext4_ext_path *path, @@ -892,8 +911,9 @@ out: } /* - * routine finds empty index and adds new leaf. if no free index found - * then it requests in-depth growing + * ext4_ext_create_new_leaf: + * finds empty index and adds new leaf. + * if no free index is found, then it requests in-depth growing. */ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode, struct ext4_ext_path *path, @@ -912,8 +932,8 @@ repeat: curp--; } - /* we use already allocated block for index block - * so, subsequent data blocks should be contigoues */ + /* we use already allocated block for index block, + * so subsequent data blocks should be contiguous */ if (EXT_HAS_FREE_INDEX(curp)) { /* if we found index with free entry, then use that * entry: create all needed subtree and add new leaf */ @@ -943,12 +963,12 @@ repeat: } /* - * only first (depth 0 -> 1) produces free space - * in all other cases we have to split growed tree + * only first (depth 0 -> 1) produces free space; + * in all other cases we have to split the grown tree */ depth = ext_depth(inode); if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) { - /* now we need split */ + /* now we need to split */ goto repeat; } } @@ -958,10 +978,11 @@ out: } /* - * returns allocated block in subsequent extent or EXT_MAX_BLOCK - * NOTE: it consider block number from index entry as - * allocated block. thus, index entries have to be consistent - * with leafs + * ext4_ext_next_allocated_block: + * returns allocated block in subsequent extent or EXT_MAX_BLOCK. + * NOTE: it considers block number from index entry as + * allocated block. Thus, index entries have to be consistent + * with leaves. */ static unsigned long ext4_ext_next_allocated_block(struct ext4_ext_path *path) @@ -993,6 +1014,7 @@ ext4_ext_next_allocated_block(struct ext4_ext_path *path) } /* + * ext4_ext_next_leaf_block: * returns first allocated block from next leaf or EXT_MAX_BLOCK */ static unsigned ext4_ext_next_leaf_block(struct inode *inode, @@ -1021,8 +1043,9 @@ static unsigned ext4_ext_next_leaf_block(struct inode *inode, } /* - * if leaf gets modified and modified extent is first in the leaf - * then we have to correct all indexes above + * ext4_ext_correct_indexes: + * if leaf gets modified and modified extent is first in the leaf, + * then we have to correct all indexes above. * TODO: do we need to correct tree in all cases? */ int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode, @@ -1050,7 +1073,7 @@ int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode, } /* - * TODO: we need correction if border is smaller then current one + * TODO: we need correction if border is smaller than current one */ k = depth - 1; border = path[depth].p_ext->ee_block; @@ -1085,7 +1108,7 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, /* * To allow future support for preallocated extents to be added * as an RO_COMPAT feature, refuse to merge to extents if - * can result in the top bit of ee_len being set + * this can result in the top bit of ee_len being set. */ if (le16_to_cpu(ex1->ee_len) + le16_to_cpu(ex2->ee_len) > EXT_MAX_LEN) return 0; @@ -1100,9 +1123,10 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, } /* - * this routine tries to merge requsted extent into the existing - * extent or inserts requested extent as new one into the tree, - * creating new leaf in no-space case + * ext4_ext_insert_extent: + * tries to merge requsted extent into the existing extent or + * inserts requested extent as new one into the tree, + * creating new leaf in the no-space case. */ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode, struct ext4_ext_path *path, @@ -1163,8 +1187,8 @@ repeat: } /* - * there is no free space in found leaf - * we're gonna add new leaf in the tree + * There is no free space in the found leaf. + * We're gonna add a new leaf in the tree. */ err = ext4_ext_create_new_leaf(handle, inode, path, newext); if (err) @@ -1377,7 +1401,8 @@ ext4_ext_put_in_cache(struct inode *inode, __u32 block, } /* - * this routine calculate boundaries of the gap requested block fits into + * ext4_ext_put_gap_in_cache: + * calculate boundaries of the gap that the requested block fits into * and cache this gap */ static inline void @@ -1452,9 +1477,10 @@ ext4_ext_in_cache(struct inode *inode, unsigned long block, } /* - * routine removes index from the index block - * it's used in truncate case only. thus all requests are for - * last index in the block only + * ext4_ext_rm_idx: + * removes index from the index block. + * It's used in truncate case only, thus all requests are for + * last index in the block only. */ int ext4_ext_rm_idx(handle_t *handle, struct inode *inode, struct ext4_ext_path *path) @@ -1480,11 +1506,12 @@ int ext4_ext_rm_idx(handle_t *handle, struct inode *inode, } /* - * This routine returns max. credits extent tree can consume. + * ext4_ext_calc_credits_for_insert: + * This routine returns max. credits that the extent tree can consume. * It should be OK for low-performance paths like ->writepage() - * To allow many writing process to fit a single transaction, - * caller should calculate credits under truncate_mutex and - * pass actual path. + * To allow many writing processes to fit into a single transaction, + * the caller should calculate credits under truncate_mutex and + * pass the actual path. */ int inline ext4_ext_calc_credits_for_insert(struct inode *inode, struct ext4_ext_path *path) @@ -1500,9 +1527,9 @@ int inline ext4_ext_calc_credits_for_insert(struct inode *inode, } /* - * given 32bit logical block (4294967296 blocks), max. tree + * given 32-bit logical block (4294967296 blocks), max. tree * can be 4 levels in depth -- 4 * 340^4 == 53453440000. - * let's also add one more level for imbalance. + * Let's also add one more level for imbalance. */ depth = 5; @@ -1510,13 +1537,13 @@ int inline ext4_ext_calc_credits_for_insert(struct inode *inode, needed = 2; /* - * tree can be full, so it'd need to grow in depth: + * tree can be full, so it would need to grow in depth: * allocation + old root + new root */ needed += 2 + 1 + 1; /* - * Index split can happen, we'd need: + * Index split can happen, we would need: * allocate intermediate indexes (bitmap + group) * + change two blocks at each level, but root (already included) */ @@ -1634,7 +1661,7 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode, BUG_ON(b != ex_ee_block + ex_ee_len - 1); } - /* at present, extent can't cross block group */ + /* at present, extent can't cross block group: */ /* leaf + bitmap + group desc + sb + inode */ credits = 5; if (ex == EXT_FIRST_EXTENT(eh)) { @@ -1660,7 +1687,7 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode, goto out; if (num == 0) { - /* this extent is removed entirely mark slot unused */ + /* this extent is removed; mark slot entirely unused */ ext4_ext_store_pblock(ex, 0); eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1); } @@ -1692,7 +1719,8 @@ out: } /* - * returns 1 if current index have to be freed (even partial) + * ext4_ext_more_to_rm: + * returns 1 if current index has to be freed (even partial) */ static int inline ext4_ext_more_to_rm(struct ext4_ext_path *path) @@ -1703,7 +1731,7 @@ ext4_ext_more_to_rm(struct ext4_ext_path *path) return 0; /* - * if truncate on deeper level happened it it wasn't partial + * if truncate on deeper level happened, it wasn't partial, * so we have to consider current index for truncation */ if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block) @@ -1729,8 +1757,8 @@ int ext4_ext_remove_space(struct inode *inode, unsigned long start) ext4_ext_invalidate_cache(inode); /* - * we start scanning from right side freeing all the blocks - * after i_size and walking into the deep + * We start scanning from right side, freeing all the blocks + * after i_size and walking into the tree depth-wise. */ path = kmalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL); if (path == NULL) { @@ -1749,7 +1777,7 @@ int ext4_ext_remove_space(struct inode *inode, unsigned long start) if (i == depth) { /* this is leaf block */ err = ext4_ext_rm_leaf(handle, inode, path, start); - /* root level have p_bh == NULL, brelse() eats this */ + /* root level has p_bh == NULL, brelse() eats this */ brelse(path[i].p_bh); path[i].p_bh = NULL; i--; @@ -1772,14 +1800,14 @@ int ext4_ext_remove_space(struct inode *inode, unsigned long start) BUG_ON(path[i].p_hdr->eh_magic != EXT4_EXT_MAGIC); if (!path[i].p_idx) { - /* this level hasn't touched yet */ + /* this level hasn't been touched yet */ path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr); path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1; ext_debug("init index ptr: hdr 0x%p, num %d\n", path[i].p_hdr, le16_to_cpu(path[i].p_hdr->eh_entries)); } else { - /* we've already was here, see at next index */ + /* we were already here, see at next index */ path[i].p_idx--; } @@ -1799,19 +1827,19 @@ int ext4_ext_remove_space(struct inode *inode, unsigned long start) break; } - /* put actual number of indexes to know is this - * number got changed at the next iteration */ + /* save actual number of indexes since this + * number is changed at the next iteration */ path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries); i++; } else { - /* we finish processing this index, go up */ + /* we finished processing this index, go up */ if (path[i].p_hdr->eh_entries == 0 && i > 0) { - /* index is empty, remove it + /* index is empty, remove it; * handle must be already prepared by the * truncatei_leaf() */ err = ext4_ext_rm_idx(handle, inode, path + i); } - /* root level have p_bh == NULL, brelse() eats this */ + /* root level has p_bh == NULL, brelse() eats this */ brelse(path[i].p_bh); path[i].p_bh = NULL; i--; @@ -1822,8 +1850,8 @@ int ext4_ext_remove_space(struct inode *inode, unsigned long start) /* TODO: flexible tree reduction should be here */ if (path->p_hdr->eh_entries == 0) { /* - * truncate to zero freed all the tree - * so, we need to correct eh_depth + * truncate to zero freed all the tree, + * so we need to correct eh_depth */ err = ext4_ext_get_access(handle, inode, path); if (err == 0) { @@ -1912,7 +1940,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, if (goal == EXT4_EXT_CACHE_GAP) { if (!create) { /* block isn't allocated yet and - * user don't want to allocate it */ + * user doesn't want to allocate it */ goto out2; } /* we should allocate requested block */ @@ -1921,7 +1949,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, newblock = iblock - le32_to_cpu(newex.ee_block) + ext_pblock(&newex); - /* number of remain blocks in the extent */ + /* number of remaining blocks in the extent */ allocated = le16_to_cpu(newex.ee_len) - (iblock - le32_to_cpu(newex.ee_block)); goto out; @@ -1941,8 +1969,8 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, depth = ext_depth(inode); /* - * consistent leaf must not be empty - * this situations is possible, though, _during_ tree modification + * consistent leaf must not be empty; + * this situation is possible, though, _during_ tree modification; * this is why assert can't be put in ext4_ext_find_extent() */ BUG_ON(path[depth].p_ext == NULL && depth != 0); @@ -1960,10 +1988,10 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, */ if (ee_len > EXT_MAX_LEN) goto out2; - /* if found exent covers block, simple return it */ + /* if found extent covers block, simply return it */ if (iblock >= ee_block && iblock < ee_block + ee_len) { newblock = iblock - ee_block + ee_start; - /* number of remain blocks in the extent */ + /* number of remaining blocks in the extent */ allocated = ee_len - (iblock - ee_block); ext_debug("%d fit into %lu:%d -> "E3FSBLK"\n", (int) iblock, ee_block, ee_len, newblock); @@ -1974,17 +2002,18 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode, } /* - * requested block isn't allocated yet + * requested block isn't allocated yet; * we couldn't try to create block if create flag is zero */ if (!create) { - /* put just found gap into cache to speedup subsequest reqs */ + /* put just found gap into cache to speed up + * subsequent requests */ ext4_ext_put_gap_in_cache(inode, path, iblock); goto out2; } /* * Okay, we need to do block allocation. Lazily initialize the block - * allocation info here if necessary + * allocation info here if necessary. */ if (S_ISREG(inode->i_mode) && (!EXT4_I(inode)->i_block_alloc_info)) ext4_init_block_alloc_info(inode); @@ -2062,9 +2091,9 @@ void ext4_ext_truncate(struct inode * inode, struct page *page) ext4_ext_invalidate_cache(inode); /* - * TODO: optimization is possible here - * probably we need not scaning at all, - * because page truncation is enough + * TODO: optimization is possible here. + * Probably we need not scan at all, + * because page truncation is enough. */ if (ext4_orphan_add(handle, inode)) goto out_stop; @@ -2078,13 +2107,13 @@ void ext4_ext_truncate(struct inode * inode, struct page *page) err = ext4_ext_remove_space(inode, last_block); /* In a multi-transaction truncate, we only make the final - * transaction synchronous */ + * transaction synchronous. */ if (IS_SYNC(inode)) handle->h_sync = 1; out_stop: /* - * If this was a simple ftruncate(), and the file will remain alive + * If this was a simple ftruncate() and the file will remain alive, * then we need to clear up the orphan record which we created above. * However, if this was a real unlink then we were called by * ext4_delete_inode(), and we allow that function to clean up the @@ -2098,7 +2127,8 @@ out_stop: } /* - * this routine calculate max number of blocks we could modify + * ext4_ext_writepage_trans_blocks: + * calculate max number of blocks we could modify * in order to allocate new block for an inode */ int ext4_ext_writepage_trans_blocks(struct inode *inode, int num) @@ -2107,7 +2137,7 @@ int ext4_ext_writepage_trans_blocks(struct inode *inode, int num) needed = ext4_ext_calc_credits_for_insert(inode, NULL); - /* caller want to allocate num blocks, but note it includes sb */ + /* caller wants to allocate num blocks, but note it includes sb */ needed = needed * num - (num - 1); #ifdef CONFIG_QUOTA |