}
/*
+ * The ext4_ind_get_blocks() function handles non-extents inodes
+ * (i.e., using the traditional indirect/double-indirect i_blocks
+ * scheme) for ext4_get_blocks().
+ *
* Allocation strategy is simple: if we have to allocate something, we will
* have to go the whole way to leaf. So let's do it before attaching anything
* to tree, set linkage between the newborn blocks, write them if sync is
* return = 0, if plain lookup failed.
* return < 0, error case.
*
- *
- * Need to be called with
- * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
- * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
+ * The ext4_ind_get_blocks() function should be called with
+ * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem
+ * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or
+ * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
+ * blocks.
*/
static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
ext4_lblk_t iblock, unsigned int maxblocks,
struct buffer_head *bh_result,
- int create, int extend_disksize)
+ int flags)
{
int err = -EIO;
ext4_lblk_t offsets[4];
J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
- J_ASSERT(handle != NULL || create == 0);
+ J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
depth = ext4_block_to_path(inode, iblock, offsets,
&blocks_to_boundary);
}
/* Next simple case - plain lookup or failed read of indirect block */
- if (!create || err == -EIO)
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO)
goto cleanup;
/*
* protect it if you're about to implement concurrent
* ext4_get_block() -bzzz
*/
- if (!err && extend_disksize) {
+ if (!err && (flags & EXT4_GET_BLOCKS_EXTEND_DISKSIZE)) {
disksize = ((loff_t) iblock + count) << inode->i_blkbits;
if (disksize > i_size_read(inode))
disksize = i_size_read(inode);
}
/*
- * The ext4_get_blocks_wrap() function try to look up the requested blocks,
+ * The ext4_get_blocks() function tries to look up the requested blocks,
* and returns if the blocks are already mapped.
*
* Otherwise it takes the write lock of the i_data_sem and allocate blocks
*
* It returns the error in case of allocation failure.
*/
-int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
- unsigned int max_blocks, struct buffer_head *bh,
- int create, int extend_disksize, int flag)
+int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
+ unsigned int max_blocks, struct buffer_head *bh,
+ int flags)
{
int retval;
clear_buffer_unwritten(bh);
/*
- * Try to see if we can get the block without requesting
- * for new file system block.
+ * Try to see if we can get the block without requesting a new
+ * file system block.
*/
down_read((&EXT4_I(inode)->i_data_sem));
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, 0, 0);
+ bh, 0);
} else {
retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
- bh, 0, 0);
+ bh, 0);
}
up_read((&EXT4_I(inode)->i_data_sem));
/* If it is only a block(s) look up */
- if (!create)
+ if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
return retval;
/*
* let the underlying get_block() function know to
* avoid double accounting
*/
- if (flag)
+ if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
EXT4_I(inode)->i_delalloc_reserved_flag = 1;
/*
* We need to check for EXT4 here because migrate
*/
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, create, extend_disksize);
+ bh, flags);
} else {
retval = ext4_ind_get_blocks(handle, inode, block,
- max_blocks, bh, create, extend_disksize);
+ max_blocks, bh, flags);
if (retval > 0 && buffer_new(bh)) {
/*
}
}
- if (flag) {
+ if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) {
EXT4_I(inode)->i_delalloc_reserved_flag = 0;
/*
* Update reserved blocks/metadata blocks
started = 1;
}
- ret = ext4_get_blocks_wrap(handle, inode, iblock,
- max_blocks, bh_result, create, 0, 0);
+ ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
+ create ? EXT4_GET_BLOCKS_CREATE : 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
{
struct buffer_head dummy;
int fatal = 0, err;
+ int flags = EXT4_GET_BLOCKS_EXTEND_DISKSIZE;
J_ASSERT(handle != NULL || create == 0);
dummy.b_state = 0;
dummy.b_blocknr = -1000;
buffer_trace_init(&dummy.b_history);
- err = ext4_get_blocks_wrap(handle, inode, block, 1,
- &dummy, create, 1, 0);
+ if (create)
+ flags |= EXT4_GET_BLOCKS_CREATE;
+ err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
/*
- * ext4_get_blocks_wrap() returns number of blocks
- * mapped. 0 in case of a HOLE.
+ * ext4_get_blocks() returns number of blocks mapped. 0 in
+ * case of a HOLE.
*/
if (err > 0) {
if (err > 1)
return;
}
-#define EXT4_DELALLOC_RSVED 1
+/*
+ * This function is used by mpage_da_map_blocks(). We separate it out
+ * as a separate function just to make life easier, and because
+ * mpage_da_map_blocks() used to be a generic function that took a
+ * get_block_t.
+ */
static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result)
{
handle = ext4_journal_current_handle();
BUG_ON(!handle);
- ret = ext4_get_blocks_wrap(handle, inode, iblock, max_blocks,
- bh_result, 1, 0, EXT4_DELALLOC_RSVED);
+ ret = ext4_get_blocks(handle, inode, iblock, max_blocks,
+ bh_result, EXT4_GET_BLOCKS_CREATE|
+ EXT4_GET_BLOCKS_DELALLOC_RESERVE);
if (ret <= 0)
return ret;
/*
* Update on-disk size along with block allocation we don't
- * use 'extend_disksize' as size may change within already
- * allocated block -bzzz
+ * use EXT4_GET_BLOCKS_EXTEND_DISKSIZE as size may change
+ * within already allocated block -bzzz
*/
disksize = ((loff_t) iblock + ret) << inode->i_blkbits;
if (disksize > i_size_read(inode))
return 0;
/*
* We need to make sure the BH_Delay flag is passed down to
- * ext4_da_get_block_write(), since it calls
- * ext4_get_blocks_wrap() with the EXT4_DELALLOC_RSVED flag.
- * This flag causes ext4_get_blocks_wrap() to call
+ * ext4_da_get_block_write(), since it calls ext4_get_blocks()
+ * with the EXT4_GET_BLOCKS_DELALLOC_RESERVE flag. This flag
+ * causes ext4_get_blocks() to call
* ext4_da_update_reserve_space() if the passed buffer head
* has the BH_Delay flag set. In the future, once we clean up
- * the interfaces to ext4_get_blocks_wrap(), we should pass in
- * a separate flag which requests that the delayed allocation
+ * the interfaces to ext4_get_blocks(), we should pass in a
+ * separate flag which requests that the delayed allocation
* statistics should be updated, instead of depending on the
* state information getting passed down via the map_bh's
- * state bitmasks plus the magic EXT4_DELALLOC_RSVED flag.
+ * state bitmasks plus the magic
+ * EXT4_GET_BLOCKS_DELALLOC_RESERVE flag.
*/
new.b_state = mpd->b_state & (1 << BH_Delay);
new.b_blocknr = 0;
}
/*
- * this is a special callback for ->write_begin() only
- * it's intention is to return mapped block or reserve space
+ * This is a special get_blocks_t callback which is used by
+ * ext4_da_write_begin(). It will either return mapped block or
+ * reserve space for a single block.
*
* For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
* We also have b_blocknr = -1 and b_bdev initialized properly
* For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
* We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
* initialized properly.
- *
*/
static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
* preallocated blocks are unmapped but should treated
* the same as allocated blocks.
*/
- ret = ext4_get_blocks_wrap(NULL, inode, iblock, 1, bh_result, 0, 0, 0);
+ 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 */
/*
return ret;
}
-static int ext4_normal_get_block_write(struct inode *inode, sector_t iblock,
+/*
+ * This function is used as a standard get_block_t calback function
+ * when there is no desire to allocate any blocks. It is used as a
+ * callback function for block_prepare_write(), nobh_writepage(), and
+ * block_write_full_page(). These functions should only try to map a
+ * single block at a time.
+ *
+ * Since this function doesn't do block allocations even if the caller
+ * requests it by passing in create=1, it is critically important that
+ * any caller checks to make sure that any buffer heads are returned
+ * by this function are either all already mapped or marked for
+ * delayed allocation before calling nobh_writepage() or
+ * block_write_full_page(). Otherwise, b_blocknr could be left
+ * unitialized, and the page write functions will be taken by
+ * surprise.
+ */
+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_wrap(NULL, inode, iblock, max_blocks,
- bh_result, 0, 0, 0);
+ ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
+ BUG_ON(create && ret == 0);
if (ret > 0) {
bh_result->b_size = (ret << inode->i_blkbits);
ret = 0;
}
/*
- * get called vi ext4_da_writepages after taking page lock (have journal handle)
- * get called via journal_submit_inode_data_buffers (no journal handle)
- * get called via shrink_page_list via pdflush (no journal handle)
- * or grab_page_cache when doing write_begin (have journal handle)
+ * This function can get called via...
+ * - ext4_da_writepages after taking page lock (have journal handle)
+ * - journal_submit_inode_data_buffers (no journal handle)
+ * - shrink_page_list via pdflush (no journal handle)
+ * - grab_page_cache when doing write_begin (have journal handle)
*/
static int ext4_da_writepage(struct page *page,
struct writeback_control *wbc)
* do block allocation here.
*/
ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
- ext4_normal_get_block_write);
+ noalloc_get_block_write);
if (!ret) {
page_bufs = page_buffers(page);
/* check whether all are mapped and non delay */
}
if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
- ret = nobh_writepage(page, ext4_normal_get_block_write, wbc);
+ ret = nobh_writepage(page, noalloc_get_block_write, wbc);
else
- ret = block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ ret = block_write_full_page(page, noalloc_get_block_write,
+ wbc);
return ret;
}
*pagep = page;
ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
- ext4_da_get_block_prep);
+ ext4_da_get_block_prep);
if (ret < 0) {
unlock_page(page);
ext4_journal_stop(handle);
struct inode *inode = page->mapping->host;
if (test_opt(inode->i_sb, NOBH))
- return nobh_writepage(page,
- ext4_normal_get_block_write, wbc);
+ return nobh_writepage(page, noalloc_get_block_write, wbc);
else
- return block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ return block_write_full_page(page, noalloc_get_block_write,
+ wbc);
}
static int ext4_normal_writepage(struct page *page,
int err;
ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
- ext4_normal_get_block_write);
+ noalloc_get_block_write);
if (ret != 0)
goto out_unlock;
* really know unless we go poke around in the buffer_heads.
* But block_write_full_page will do the right thing.
*/
- return block_write_full_page(page,
- ext4_normal_get_block_write,
- wbc);
+ return block_write_full_page(page, noalloc_get_block_write,
+ wbc);
}
no_write:
redirty_page_for_writepage(wbc, page);
* Calculate the journal credits for a chunk of data modification.
*
* This is called from DIO, fallocate or whoever calling
- * ext4_get_blocks_wrap() to map/allocate a chunk of contigous disk blocks.
+ * ext4_get_blocks() to map/allocate a chunk of contigous disk blocks.
*
* journal buffers for data blocks are not included here, as DIO
* and fallocate do no need to journal data buffers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff