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ext4: move trans handling and completion deferal out of _ext4_get_block 

There is no need to handle starting of a transaction and deferal of DIO
completion in _ext4_get_block() function. We can move this out to get
block functions for direct IO that need it. That way we can add stricter
checks verifying things work as we expect.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara 2016-03-08 23:35:46 -05:00 committed by Theodore Ts'o
parent 705965bd6d
commit efe70c2951
1 changed files with 59 additions and 32 deletions
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91
fs/ext4/inode.c
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@ -714,16 +714,11 @@ static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
cmpxchg(&bh->b_state, old_state, new_state) != old_state));
}
/* 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, int flags)
{
handle_t *handle = ext4_journal_current_handle();
struct ext4_map_blocks map;
int ret = 0, started = 0;
int dio_credits;
int ret = 0;
if (ext4_has_inline_data(inode))
return -ERANGE;
@ -731,33 +726,14 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
map.m_lblk = iblock;
map.m_len = bh->b_size >> inode->i_blkbits;
if (flags && !handle) {
/* Direct IO write... */
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, EXT4_HT_MAP_BLOCKS,
dio_credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
return ret;
}
started = 1;
}
ret = ext4_map_blocks(handle, inode, &map, flags);
ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
flags);
if (ret > 0) {
ext4_io_end_t *io_end = ext4_inode_aio(inode);
map_bh(bh, inode->i_sb, map.m_pblk);
ext4_update_bh_state(bh, map.m_flags);
if (io_end && io_end->flag & EXT4_IO_END_UNWRITTEN)
set_buffer_defer_completion(bh);
bh->b_size = inode->i_sb->s_blocksize * map.m_len;
ret = 0;
}
if (started)
ext4_journal_stop(handle);
return ret;
}
@ -782,12 +758,42 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
EXT4_GET_BLOCKS_IO_CREATE_EXT);
}
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
static handle_t *start_dio_trans(struct inode *inode,
struct buffer_head *bh_result)
{
int dio_credits;
/* Trim mapping request to maximum we can map at once for DIO */
if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
dio_credits = ext4_chunk_trans_blocks(inode,
bh_result->b_size >> inode->i_blkbits);
return ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
}
/* Get block function for DIO reads and writes to inodes without extents */
int ext4_dio_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_t *handle;
int ret;
/* We don't expect handle for direct IO */
WARN_ON_ONCE(ext4_journal_current_handle());
if (create) {
handle = start_dio_trans(inode, bh);
if (IS_ERR(handle))
return PTR_ERR(handle);
}
ret = _ext4_get_block(inode, iblock, bh,
create ? EXT4_GET_BLOCKS_CREATE : 0);
if (create)
ext4_journal_stop(handle);
return ret;
}
/*
@ -798,10 +804,28 @@ int ext4_dio_get_block(struct inode *inode, sector_t iblock,
static int ext4_dio_get_block_unwritten(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
handle_t *handle;
int ret;
ext4_debug("ext4_dio_get_block_unwritten: inode %lu, create flag %d\n",
inode->i_ino, create);
return _ext4_get_block(inode, iblock, bh_result,
EXT4_GET_BLOCKS_IO_CREATE_EXT);
/* We don't expect handle for direct IO */
WARN_ON_ONCE(ext4_journal_current_handle());
handle = start_dio_trans(inode, bh_result);
if (IS_ERR(handle))
return PTR_ERR(handle);
ret = _ext4_get_block(inode, iblock, bh_result,
EXT4_GET_BLOCKS_IO_CREATE_EXT);
ext4_journal_stop(handle);
if (!ret && buffer_unwritten(bh_result)) {
ext4_io_end_t *io_end = ext4_inode_aio(inode);
set_buffer_defer_completion(bh_result);
WARN_ON_ONCE(io_end && !(io_end->flag & EXT4_IO_END_UNWRITTEN));
}
return ret;
}
static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
@ -811,12 +835,15 @@ static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
inode->i_ino, create);
/* We don't expect handle for direct IO */
WARN_ON_ONCE(ext4_journal_current_handle());
ret = _ext4_get_block(inode, iblock, bh_result, 0);
/*
* Blocks should have been preallocated! ext4_file_write_iter() checks
* that.
*/
WARN_ON_ONCE(!buffer_mapped(bh_result));
WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
return ret;
}