#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;
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;
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));
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));
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;
}
}
/*
- * 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)
}
/*
- * 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)
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;
}
}
/*
- * 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,
}
/*
- * 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,
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 {
}
/*
- * 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)
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 */
}
/*
- * 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,
}
/*
- * 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,
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 */
}
/*
- * 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;
}
}
}
/*
- * 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)
}
/*
+ * 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,
}
/*
- * 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,
}
/*
- * 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;
/*
* 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;
}
/*
- * 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,
}
/*
- * 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)
}
/*
- * 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
}
/*
- * 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)
}
/*
- * 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)
}
/*
- * 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;
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)
*/
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)) {
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);
}
}
/*
- * 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)
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)
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) {
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--;
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--;
}
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--;
/* 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) {
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 */
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;
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);
*/
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);
}
/*
- * 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);
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;
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
}
/*
- * 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)
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
projects / linux-2.6 / commitdiff