Commit f3bd1f3f authored by Mingming Cao's avatar Mingming Cao Committed by Theodore Ts'o
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ext4: journal credits reservation fixes for DIO, fallocate



DIO and fallocate credit calculation is different than writepage, as
they do start a new journal right for each call to ext4_get_blocks_wrap().
This patch uses the helper function in DIO and fallocate case, passing
a flag indicating that the modified data are contigous thus could account
less indirect/index blocks.

This patch also fixed the journal credit reservation for direct I/O
(DIO).  Previously the estimated credits for DIO only was calculated for
non-extent files, which was not enough if the file is extent-based.

Also fixed was fallocate double-counting credits for modifying the the
superblock.

Signed-off-by: default avatarMingming Cao <cmm@us.ibm.com>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent ee12b630
......@@ -1073,6 +1073,7 @@ extern void ext4_get_inode_flags(struct ext4_inode_info *);
extern void ext4_set_aops(struct inode *inode);
extern int ext4_writepage_trans_blocks(struct inode *);
extern int ext4_meta_trans_blocks(struct inode *, int nrblocks, int idxblocks);
extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
......
......@@ -1758,7 +1758,7 @@ int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int num,
{
if (path) {
int depth = ext_depth(inode);
int ret;
int ret = 0;
/* probably there is space in leaf? */
if (le16_to_cpu(path[depth].p_hdr->eh_entries)
......@@ -1777,7 +1777,7 @@ int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int num,
}
}
return ext4_meta_trans_blocks(inode, num, 1);
return ext4_chunk_trans_blocks(inode, num);
}
/*
......@@ -2810,7 +2810,7 @@ void ext4_ext_truncate(struct inode *inode)
/*
* probably first extent we're gonna free will be last in block
*/
err = ext4_writepage_trans_blocks(inode) + 3;
err = ext4_writepage_trans_blocks(inode);
handle = ext4_journal_start(inode, err);
if (IS_ERR(handle))
return;
......@@ -2923,10 +2923,9 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- block;
/*
* credits to insert 1 extent into extent tree + buffers to be able to
* modify 1 super block, 1 block bitmap and 1 group descriptor.
* credits to insert 1 extent into extent tree
*/
credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + 3;
credits = ext4_chunk_trans_blocks(inode, max_blocks);
mutex_lock(&inode->i_mutex);
retry:
while (ret >= 0 && ret < max_blocks) {
......
......@@ -1044,18 +1044,6 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
}
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
/*
* Number of credits we need for writing DIO_MAX_BLOCKS:
* We need sb + group descriptor + bitmap + inode -> 4
* For B blocks with A block pointers per block we need:
* 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
* If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
*/
#define DIO_CREDITS 25
/*
* The ext4_get_blocks_wrap() function try to look up the requested blocks,
* and returns if the blocks are already mapped.
......@@ -1167,19 +1155,23 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
return retval;
}
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
static int ext4_get_block(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
handle_t *handle = ext4_journal_current_handle();
int ret = 0, started = 0;
unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
int dio_credits;
if (create && !handle) {
/* Direct IO write... */
if (max_blocks > DIO_MAX_BLOCKS)
max_blocks = DIO_MAX_BLOCKS;
handle = ext4_journal_start(inode, DIO_CREDITS +
2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
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;
......@@ -2243,7 +2235,7 @@ static int ext4_da_writepage(struct page *page,
* for DIO, writepages, and truncate
*/
#define EXT4_MAX_WRITEBACK_PAGES DIO_MAX_BLOCKS
#define EXT4_MAX_WRITEBACK_CREDITS DIO_CREDITS
#define EXT4_MAX_WRITEBACK_CREDITS 25
static int ext4_da_writepages(struct address_space *mapping,
struct writeback_control *wbc)
......@@ -4441,7 +4433,8 @@ int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
/*
* Calulate the total number of credits to reserve to fit
* the modification of a single pages into a single transaction
* the modification of a single pages into a single transaction,
* which may include multiple chunks of block allocations.
*
* This could be called via ext4_write_begin() or later
* ext4_da_writepages() in delalyed allocation case.
......@@ -4449,11 +4442,6 @@ int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk)
* In both case it's possible that we could allocating multiple
* chunks of blocks. We need to consider the worse case, when
* one new block per extent.
*
* For Direct IO and fallocate, the journal credits reservation
* is based on one single extent allocation, so they could use
* EXT4_DATA_TRANS_BLOCKS to get the needed credit to log a single
* chunk of allocation needs.
*/
int ext4_writepage_trans_blocks(struct inode *inode)
{
......@@ -4467,6 +4455,21 @@ int ext4_writepage_trans_blocks(struct inode *inode)
ret += bpp;
return ret;
}
/*
* 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.
*
* journal buffers for data blocks are not included here, as DIO
* and fallocate do no need to journal data buffers.
*/
int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
{
return ext4_meta_trans_blocks(inode, nrblocks, 1);
}
/*
* The caller must have previously called ext4_reserve_inode_write().
* Give this, we know that the caller already has write access to iloc->bh.
......
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