Commit f063db5e authored by Matthew Bobrowski's avatar Matthew Bobrowski Committed by Theodore Ts'o

ext4: split IOMAP_WRITE branch in ext4_iomap_begin() into helper

In preparation for porting across the ext4 direct I/O path over to the
iomap infrastructure, split up the IOMAP_WRITE branch that's currently
within ext4_iomap_begin() into a separate helper
ext4_alloc_iomap(). This way, when we add in the necessary code for
direct I/O, we don't end up with ext4_iomap_begin() becoming a
monstrous twisty maze.
Signed-off-by: default avatarMatthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarRitesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/50eef383add1ea529651640574111076c55aca9f.1572949325.git.mbobrowski@mbobrowski.orgSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent c8fdfe29
......@@ -3493,6 +3493,63 @@ static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
}
}
static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
unsigned int flags)
{
handle_t *handle;
u8 blkbits = inode->i_blkbits;
int ret, dio_credits, retries = 0;
/*
* Trim the mapping request to the maximum value that we can map at
* once for direct I/O.
*/
if (map->m_len > DIO_MAX_BLOCKS)
map->m_len = DIO_MAX_BLOCKS;
dio_credits = ext4_chunk_trans_blocks(inode, map->m_len);
retry:
/*
* Either we allocate blocks and then don't get an unwritten extent, so
* in that case we have reserved enough credits. Or, the blocks are
* already allocated and unwritten. In that case, the extent conversion
* fits into the credits as well.
*/
handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
if (IS_ERR(handle))
return PTR_ERR(handle);
ret = ext4_map_blocks(handle, inode, map, EXT4_GET_BLOCKS_CREATE_ZERO);
if (ret < 0)
goto journal_stop;
/*
* If we've allocated blocks beyond EOF, we need to ensure that they're
* truncated if we crash before updating the inode size metadata within
* ext4_iomap_end(). For faults, we don't need to do that (and cannot
* due to orphan list operations needing an inode_lock()). If we happen
* to instantiate blocks beyond EOF, it is because we race with a
* truncate operation, which already has added the inode onto the
* orphan list.
*/
if (!(flags & IOMAP_FAULT) && map->m_lblk + map->m_len >
(i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
int err;
err = ext4_orphan_add(handle, inode);
if (err < 0)
ret = err;
}
journal_stop:
ext4_journal_stop(handle);
if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
return ret;
}
static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
unsigned flags, struct iomap *iomap, struct iomap *srcmap)
{
......@@ -3553,61 +3610,13 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}
}
} else if (flags & IOMAP_WRITE) {
int dio_credits;
handle_t *handle;
int retries = 0;
/* Trim mapping request to maximum we can map at once for DIO */
if (map.m_len > DIO_MAX_BLOCKS)
map.m_len = DIO_MAX_BLOCKS;
dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
retry:
/*
* Either we allocate blocks and then we don't get unwritten
* extent so we have reserved enough credits, or the blocks
* are already allocated and unwritten and in that case
* extent conversion fits in the credits as well.
*/
handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
dio_credits);
if (IS_ERR(handle))
return PTR_ERR(handle);
ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_CREATE_ZERO);
if (ret < 0) {
ext4_journal_stop(handle);
if (ret == -ENOSPC &&
ext4_should_retry_alloc(inode->i_sb, &retries))
goto retry;
return ret;
}
/*
* If we added blocks beyond i_size, we need to make sure they
* will get truncated if we crash before updating i_size in
* ext4_iomap_end(). For faults we don't need to do that (and
* even cannot because for orphan list operations inode_lock is
* required) - if we happen to instantiate block beyond i_size,
* it is because we race with truncate which has already added
* the inode to the orphan list.
*/
if (!(flags & IOMAP_FAULT) && first_block + map.m_len >
(i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
int err;
err = ext4_orphan_add(handle, inode);
if (err < 0) {
ext4_journal_stop(handle);
return err;
}
}
ext4_journal_stop(handle);
ret = ext4_iomap_alloc(inode, &map, flags);
} else {
ret = ext4_map_blocks(NULL, inode, &map, 0);
}
if (ret < 0)
return ret;
}
ext4_set_iomap(inode, iomap, &map, offset, length);
if (delalloc && iomap->type == IOMAP_HOLE)
......
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