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ext4: Convert callers of ext4_get_blocks() to use ext4_map_blocks() 

This saves a huge amount of stack space by avoiding unnecesary struct
buffer_head's from being allocated on the stack.

In addition, to make the code easier to understand, collapse and
refactor ext4_get_block(), ext4_get_block_write(),
noalloc_get_block_write(), into a single function.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2010-05-16 20:00:00 -04:00
parent e35fd6609b
commit 2ed886852a
3 changed files with 152 additions and 231 deletions
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12
fs/ext4/dir.c
View File

@ -128,14 +128,14 @@ static int ext4_readdir(struct file *filp,
offset = filp->f_pos & (sb->s_blocksize - 1);
while (!error && !stored && filp->f_pos < inode->i_size) {
ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
struct buffer_head map_bh;
struct ext4_map_blocks map;
struct buffer_head *bh = NULL;
map_bh.b_state = 0;
err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0);
map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
map.m_len = 1;
err = ext4_map_blocks(NULL, inode, &map, 0);
if (err > 0) {
pgoff_t index = map_bh.b_blocknr >>
pgoff_t index = map.m_pblk >>
(PAGE_CACHE_SHIFT - inode->i_blkbits);
if (!ra_has_index(&filp->f_ra, index))
page_cache_sync_readahead(
@ -143,7 +143,7 @@ static int ext4_readdir(struct file *filp,
&filp->f_ra, filp,
index, 1);
filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
bh = ext4_bread(NULL, inode, blk, 0, &err);
bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
}
/*

40
fs/ext4/extents.c
View File

@ -3667,13 +3667,12 @@ static void ext4_falloc_update_inode(struct inode *inode,
long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
{
handle_t *handle;
ext4_lblk_t block;
loff_t new_size;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
int retries = 0;
struct buffer_head map_bh;
struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;
/*
@ -3687,13 +3686,13 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
if (S_ISDIR(inode->i_mode))
return -ENODEV;
block = offset >> blkbits;
map.m_lblk = offset >> blkbits;
/*
* We can't just convert len to max_blocks because
* If blocksize = 4096 offset = 3072 and len = 2048
*/
max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- block;
- map.m_lblk;
/*
* credits to insert 1 extent into extent tree
*/
@ -3706,16 +3705,14 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
}
retry:
while (ret >= 0 && ret < max_blocks) {
block = block + ret;
max_blocks = max_blocks - ret;
map.m_lblk = map.m_lblk + ret;
map.m_len = max_blocks = max_blocks - ret;
handle = ext4_journal_start(inode, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
}
map_bh.b_state = 0;
ret = ext4_get_blocks(handle, inode, block,
max_blocks, &map_bh,
ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_CREATE_UNINIT_EXT);
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
@ -3729,14 +3726,14 @@ retry:
ret2 = ext4_journal_stop(handle);
break;
}
if ((block + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
if ((map.m_lblk + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
blkbits) >> blkbits))
new_size = offset + len;
else
new_size = (block + ret) << blkbits;
new_size = (map.m_lblk + ret) << blkbits;
ext4_falloc_update_inode(inode, mode, new_size,
buffer_new(&map_bh));
(map.m_flags & EXT4_MAP_NEW));
ext4_mark_inode_dirty(handle, inode);
ret2 = ext4_journal_stop(handle);
if (ret2)
@ -3765,42 +3762,39 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
ssize_t len)
{
handle_t *handle;
ext4_lblk_t block;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
struct buffer_head map_bh;
struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;
block = offset >> blkbits;
map.m_lblk = offset >> blkbits;
/*
* We can't just convert len to max_blocks because
* If blocksize = 4096 offset = 3072 and len = 2048
*/
max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- block;
max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -
map.m_lblk);
/*
* credits to insert 1 extent into extent tree
*/
credits = ext4_chunk_trans_blocks(inode, max_blocks);
while (ret >= 0 && ret < max_blocks) {
block = block + ret;
max_blocks = max_blocks - ret;
map.m_lblk += ret;
map.m_len = (max_blocks -= ret);
handle = ext4_journal_start(inode, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
}
map_bh.b_state = 0;
ret = ext4_get_blocks(handle, inode, block,
max_blocks, &map_bh,
ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_IO_CONVERT_EXT);
if (ret <= 0) {
WARN_ON(ret <= 0);
printk(KERN_ERR "%s: ext4_ext_map_blocks "
"returned error inode#%lu, block=%u, "
"max_blocks=%u", __func__,
inode->i_ino, block, max_blocks);
inode->i_ino, map.m_lblk, map.m_len);
}
ext4_mark_inode_dirty(handle, inode);
ret2 = ext4_journal_stop(handle);

331
fs/ext4/inode.c
View File

@ -1336,133 +1336,112 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
return retval;
}
int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
unsigned int max_blocks, struct buffer_head *bh,
int flags)
{
struct ext4_map_blocks map;
int ret;
map.m_lblk = block;
map.m_len = max_blocks;
ret = ext4_map_blocks(handle, inode, &map, flags);
if (ret < 0)
return ret;
bh->b_blocknr = map.m_pblk;
bh->b_size = inode->i_sb->s_blocksize * map.m_len;
bh->b_bdev = inode->i_sb->s_bdev;
bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
return ret;
}
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
static int _ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int flags)
{
handle_t *handle = ext4_journal_current_handle();
struct ext4_map_blocks map;
int ret = 0, started = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
int dio_credits;
if (create && !handle) {
map.m_lblk = iblock;
map.m_len = bh->b_size >> inode->i_blkbits;
if (flags && !handle) {
/* Direct IO write... */
if (max_blocks > DIO_MAX_BLOCKS)
max_blocks = DIO_MAX_BLOCKS;
dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
if (map.m_len > DIO_MAX_BLOCKS)
map.m_len = DIO_MAX_BLOCKS;
dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
handle = ext4_journal_start(inode, dio_credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto out;
return ret;
}
started = 1;
}
ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
create ? EXT4_GET_BLOCKS_CREATE : 0);
ret = ext4_map_blocks(handle, inode, &map, flags);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
map_bh(bh, inode->i_sb, map.m_pblk);
bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
bh->b_size = inode->i_sb->s_blocksize * map.m_len;
ret = 0;
}
if (started)
ext4_journal_stop(handle);
out:
return ret;
}
int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh, int create)
{
return _ext4_get_block(inode, iblock, bh,
create ? EXT4_GET_BLOCKS_CREATE : 0);
}
/*
* `handle' can be NULL if create is zero
*/
struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
ext4_lblk_t block, int create, int *errp)
{
struct buffer_head dummy;
struct ext4_map_blocks map;
struct buffer_head *bh;
int fatal = 0, err;
int flags = 0;
J_ASSERT(handle != NULL || create == 0);
dummy.b_state = 0;
dummy.b_blocknr = -1000;
buffer_trace_init(&dummy.b_history);
if (create)
flags |= EXT4_GET_BLOCKS_CREATE;
err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
/*
* ext4_get_blocks() returns number of blocks mapped. 0 in
* case of a HOLE.
*/
if (err > 0) {
if (err > 1)
WARN_ON(1);
err = 0;
}
*errp = err;
if (!err && buffer_mapped(&dummy)) {
struct buffer_head *bh;
bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
if (!bh) {
*errp = -EIO;
goto err;
}
if (buffer_new(&dummy)) {
J_ASSERT(create != 0);
J_ASSERT(handle != NULL);
map.m_lblk = block;
map.m_len = 1;
err = ext4_map_blocks(handle, inode, &map,
create ? EXT4_GET_BLOCKS_CREATE : 0);
/*
* Now that we do not always journal data, we should
* keep in mind whether this should always journal the
* new buffer as metadata. For now, regular file
* writes use ext4_get_block instead, so it's not a
* problem.
*/
lock_buffer(bh);
BUFFER_TRACE(bh, "call get_create_access");
fatal = ext4_journal_get_create_access(handle, bh);
if (!fatal && !buffer_uptodate(bh)) {
memset(bh->b_data, 0, inode->i_sb->s_blocksize);
set_buffer_uptodate(bh);
}
unlock_buffer(bh);
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, inode, bh);
if (!fatal)
fatal = err;
} else {
BUFFER_TRACE(bh, "not a new buffer");
}
if (fatal) {
*errp = fatal;
brelse(bh);
bh = NULL;
}
return bh;
if (err < 0)
*errp = err;
if (err <= 0)
return NULL;
*errp = 0;
bh = sb_getblk(inode->i_sb, map.m_pblk);
if (!bh) {
*errp = -EIO;
return NULL;
}
err:
return NULL;
if (map.m_flags & EXT4_MAP_NEW) {
J_ASSERT(create != 0);
J_ASSERT(handle != NULL);
/*
* Now that we do not always journal data, we should
* keep in mind whether this should always journal the
* new buffer as metadata. For now, regular file
* writes use ext4_get_block instead, so it's not a
* problem.
*/
lock_buffer(bh);
BUFFER_TRACE(bh, "call get_create_access");
fatal = ext4_journal_get_create_access(handle, bh);
if (!fatal && !buffer_uptodate(bh)) {
memset(bh->b_data, 0, inode->i_sb->s_blocksize);
set_buffer_uptodate(bh);
}
unlock_buffer(bh);
BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
err = ext4_handle_dirty_metadata(handle, inode, bh);
if (!fatal)
fatal = err;
} else {
BUFFER_TRACE(bh, "not a new buffer");
}
if (fatal) {
*errp = fatal;
brelse(bh);
bh = NULL;
}
return bh;
}
struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
@ -2050,28 +2029,23 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
/*
* mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
*
* @mpd->inode - inode to walk through
* @exbh->b_blocknr - first block on a disk
* @exbh->b_size - amount of space in bytes
* @logical - first logical block to start assignment with
*
* the function goes through all passed space and put actual disk
* block numbers into buffer heads, dropping BH_Delay and BH_Unwritten
*/
static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
struct buffer_head *exbh)
static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd,
struct ext4_map_blocks *map)
{
struct inode *inode = mpd->inode;
struct address_space *mapping = inode->i_mapping;
int blocks = exbh->b_size >> inode->i_blkbits;
sector_t pblock = exbh->b_blocknr, cur_logical;
int blocks = map->m_len;
sector_t pblock = map->m_pblk, cur_logical;
struct buffer_head *head, *bh;
pgoff_t index, end;
struct pagevec pvec;
int nr_pages, i;
index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
index = map->m_lblk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
end = (map->m_lblk + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
pagevec_init(&pvec, 0);
@ -2098,17 +2072,16 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
/* skip blocks out of the range */
do {
if (cur_logical >= logical)
if (cur_logical >= map->m_lblk)
break;
cur_logical++;
} while ((bh = bh->b_this_page) != head);
do {
if (cur_logical >= logical + blocks)
if (cur_logical >= map->m_lblk + blocks)
break;
if (buffer_delay(bh) ||
buffer_unwritten(bh)) {
if (buffer_delay(bh) || buffer_unwritten(bh)) {
BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
@ -2127,7 +2100,7 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
} else if (buffer_mapped(bh))
BUG_ON(bh->b_blocknr != pblock);
if (buffer_uninit(exbh))
if (map->m_flags & EXT4_MAP_UNINIT)
set_buffer_uninit(bh);
cur_logical++;
pblock++;
@ -2138,21 +2111,6 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
}
/*
* __unmap_underlying_blocks - just a helper function to unmap
* set of blocks described by @bh
*/
static inline void __unmap_underlying_blocks(struct inode *inode,
struct buffer_head *bh)
{
struct block_device *bdev = inode->i_sb->s_bdev;
int blocks, i;
blocks = bh->b_size >> inode->i_blkbits;
for (i = 0; i < blocks; i++)
unmap_underlying_metadata(bdev, bh->b_blocknr + i);
}
static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
sector_t logical, long blk_cnt)
{
@ -2214,7 +2172,7 @@ static void ext4_print_free_blocks(struct inode *inode)
static int mpage_da_map_blocks(struct mpage_da_data *mpd)
{
int err, blks, get_blocks_flags;
struct buffer_head new;
struct ext4_map_blocks map;
sector_t next = mpd->b_blocknr;
unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
@ -2255,15 +2213,15 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
* EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
* variables are updated after the blocks have been allocated.
*/
new.b_state = 0;
map.m_lblk = next;
map.m_len = max_blocks;
get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
if (ext4_should_dioread_nolock(mpd->inode))
get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
if (mpd->b_state & (1 << BH_Delay))
get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,
&new, get_blocks_flags);
blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
if (blks < 0) {
err = blks;
/*
@ -2305,10 +2263,13 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
}
BUG_ON(blks == 0);
new.b_size = (blks << mpd->inode->i_blkbits);
if (map.m_flags & EXT4_MAP_NEW) {
struct block_device *bdev = mpd->inode->i_sb->s_bdev;
int i;
if (buffer_new(&new))
__unmap_underlying_blocks(mpd->inode, &new);
for (i = 0; i < map.m_len; i++)
unmap_underlying_metadata(bdev, map.m_pblk + i);
}
/*
* If blocks are delayed marked, we need to
@ -2316,7 +2277,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
*/
if ((mpd->b_state & (1 << BH_Delay)) ||
(mpd->b_state & (1 << BH_Unwritten)))
mpage_put_bnr_to_bhs(mpd, next, &new);
mpage_put_bnr_to_bhs(mpd, &map);
if (ext4_should_order_data(mpd->inode)) {
err = ext4_jbd2_file_inode(handle, mpd->inode);
@ -2534,8 +2495,9 @@ static int __mpage_da_writepage(struct page *page,
* initialized properly.
*/
static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
struct buffer_head *bh, int create)
{
struct ext4_map_blocks map;
int ret = 0;
sector_t invalid_block = ~((sector_t) 0xffff);
@ -2543,16 +2505,22 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
invalid_block = ~0;
BUG_ON(create == 0);
BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
map.m_lblk = iblock;
map.m_len = 1;
/*
* first, we need to know whether the block is allocated already
* preallocated blocks are unmapped but should treated
* the same as allocated blocks.
*/
ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0);
if ((ret == 0) && !buffer_delay(bh_result)) {
/* the block isn't (pre)allocated yet, let's reserve space */
ret = ext4_map_blocks(NULL, inode, &map, 0);
if (ret < 0)
return ret;
if (ret == 0) {
if (buffer_delay(bh))
return 0; /* Not sure this could or should happen */
/*
* XXX: __block_prepare_write() unmaps passed block,
* is it OK?
@ -2562,26 +2530,26 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
/* not enough space to reserve */
return ret;
map_bh(bh_result, inode->i_sb, invalid_block);
set_buffer_new(bh_result);
set_buffer_delay(bh_result);
} else if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
if (buffer_unwritten(bh_result)) {
/* A delayed write to unwritten bh should
* be marked new and mapped. Mapped ensures
* that we don't do get_block multiple times
* when we write to the same offset and new
* ensures that we do proper zero out for
* partial write.
*/
set_buffer_new(bh_result);
set_buffer_mapped(bh_result);
}
ret = 0;
map_bh(bh, inode->i_sb, invalid_block);
set_buffer_new(bh);
set_buffer_delay(bh);
return 0;
}
return ret;
map_bh(bh, inode->i_sb, map.m_pblk);
bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
if (buffer_unwritten(bh)) {
/* A delayed write to unwritten bh should be marked
* new and mapped. Mapped ensures that we don't do
* get_block multiple times when we write to the same
* offset and new ensures that we do proper zero out
* for partial write.
*/
set_buffer_new(bh);
set_buffer_mapped(bh);
}
return 0;
}
/*
@ -2603,21 +2571,8 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
int ret = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
/*
* we don't want to do block allocation in writepage
* so call get_block_wrap with create = 0
*/
ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
}
return ret;
return _ext4_get_block(inode, iblock, bh_result, 0);
}
static int bget_one(handle_t *handle, struct buffer_head *bh)
@ -3644,46 +3599,18 @@ out:
return ret;
}
/*
* ext4_get_block used when preparing for a DIO write or buffer write.
* We allocate an uinitialized extent if blocks haven't been allocated.
* The extent will be converted to initialized after the IO is complete.
*/
static int ext4_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
handle_t *handle = ext4_journal_current_handle();
int ret = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
int dio_credits;
int started = 0;
ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
inode->i_ino, create);
/*
* ext4_get_block in prepare for a DIO write or buffer write.
* We allocate an uinitialized extent if blocks haven't been allocated.
* The extent will be converted to initialized after IO complete.
*/
create = EXT4_GET_BLOCKS_IO_CREATE_EXT;
if (!handle) {
if (max_blocks > DIO_MAX_BLOCKS)
max_blocks = DIO_MAX_BLOCKS;
dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
handle = ext4_journal_start(inode, dio_credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
goto out;
}
started = 1;
}
ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
create);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
}
if (started)
ext4_journal_stop(handle);
out:
return ret;
return _ext4_get_block(inode, iblock, bh_result,
EXT4_GET_BLOCKS_IO_CREATE_EXT);
}
static void dump_completed_IO(struct inode * inode)