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>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bf545d0..aea67d9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -714,16 +714,11 @@
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 @@
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 @@
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 @@
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 @@
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;
}