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Commit d0d856e8 authored by Randy Dunlap's avatar Randy Dunlap Committed by Linus Torvalds
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[PATCH] ext4: clean up comments in ext4-extents patch 

Signed-off-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: default avatarDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 471d4011
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Showing with 157 additions and 127 deletions
fs/ext4/extents.c
View file @ d0d856e8
......@@ -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 @@ ext4_ext_find_extent(struct inode *inode, int block, struct ext4_ext_path *path)
}
/*
* 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 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
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 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
}
/*
* 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 @@ void ext4_ext_truncate(struct inode * inode, struct page *page)
}
/*
* 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
......
include/linux/ext4_fs_extents.h
View file @ d0d856e8
......@@ -22,29 +22,29 @@
#include <linux/ext4_fs.h>
/*
* with AGRESSIVE_TEST defined capacity of index/leaf blocks
* become very little, so index split, in-depth growing and
* other hard changes happens much more often
* this is for debug purposes only
* With AGRESSIVE_TEST defined, the capacity of index/leaf blocks
* becomes very small, so index split, in-depth growing and
* other hard changes happen much more often.
* This is for debug purposes only.
*/
#define AGRESSIVE_TEST_
/*
* with EXTENTS_STATS defined number of blocks and extents
* are collected in truncate path. they'll be showed at
* umount time
* With EXTENTS_STATS defined, the number of blocks and extents
* are collected in the truncate path. They'll be shown at
* umount time.
*/
#define EXTENTS_STATS__
/*
* if CHECK_BINSEARCH defined, then results of binary search
* will be checked by linear search
* If CHECK_BINSEARCH is defined, then the results of the binary search
* will also be checked by linear search.
*/
#define CHECK_BINSEARCH__
/*
* if EXT_DEBUG is defined you can use 'extdebug' mount option
* to get lots of info what's going on
* If EXT_DEBUG is defined you can use the 'extdebug' mount option
* to get lots of info about what's going on.
*/
#define EXT_DEBUG__
#ifdef EXT_DEBUG
......@@ -54,58 +54,58 @@
#endif
/*
* if EXT_STATS is defined then stats numbers are collected
* these number will be displayed at umount time
* If EXT_STATS is defined then stats numbers are collected.
* These number will be displayed at umount time.
*/
#define EXT_STATS_
/*
* ext4_inode has i_block array (60 bytes total)
* first 12 bytes store ext4_extent_header
* the remain stores array of ext4_extent
* ext4_inode has i_block array (60 bytes total).
* The first 12 bytes store ext4_extent_header;
* the remainder stores an array of ext4_extent.
*/
/*
* this is extent on-disk structure
* it's used at the bottom of the tree
* This is the extent on-disk structure.
* It's used at the bottom of the tree.
*/
struct ext4_extent {
__le32 ee_block; /* first logical block extent covers */
__le16 ee_len; /* number of blocks covered by extent */
__le16 ee_start_hi; /* high 16 bits of physical block */
__le32 ee_start; /* low 32 bigs of physical block */
__le32 ee_start; /* low 32 bits of physical block */
};
/*
* this is index on-disk structure
* it's used at all the levels, but the bottom
* This is index on-disk structure.
* It's used at all the levels except the bottom.
*/
struct ext4_extent_idx {
__le32 ei_block; /* index covers logical blocks from 'block' */
__le32 ei_leaf; /* pointer to the physical block of the next *
* level. leaf or next index could bet here */
* level. leaf or next index could be there */
__le16 ei_leaf_hi; /* high 16 bits of physical block */
__u16 ei_unused;
};
/*
* each block (leaves and indexes), even inode-stored has header
* Each block (leaves and indexes), even inode-stored has header.
*/
struct ext4_extent_header {
__le16 eh_magic; /* probably will support different formats */
__le16 eh_entries; /* number of valid entries */
__le16 eh_max; /* capacity of store in entries */
__le16 eh_depth; /* has tree real underlaying blocks? */
__le16 eh_depth; /* has tree real underlying blocks? */
__le32 eh_generation; /* generation of the tree */
};
#define EXT4_EXT_MAGIC cpu_to_le16(0xf30a)
/*
* array of ext4_ext_path contains path to some extent
* creation/lookup routines use it for traversal/splitting/etc
* truncate uses it to simulate recursive walking
* Array of ext4_ext_path contains path to some extent.
* Creation/lookup routines use it for traversal/splitting/etc.
* Truncate uses it to simulate recursive walking.
*/
struct ext4_ext_path {
ext4_fsblk_t p_block;
......
include/linux/ext4_jbd2.h
View file @ d0d856e8
......@@ -28,8 +28,8 @@
* indirection blocks, the group and superblock summaries, and the data
* block to complete the transaction.
*
* For extents-enabled fs we may have to allocate and modify upto
* 5 levels of tree + root which is stored in inode. */
* For extents-enabled fs we may have to allocate and modify up to
* 5 levels of tree + root which are stored in the inode. */
#define EXT4_SINGLEDATA_TRANS_BLOCKS(sb) \
(EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS) \
......
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