From f063db5ee989aafe2dc9d571b5538f2a1f1cbad2 Mon Sep 17 00:00:00 2001 From: Matthew Bobrowski Date: Tue, 5 Nov 2019 23:00:14 +1100 Subject: [PATCH] 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: Matthew Bobrowski Reviewed-by: Jan Kara Reviewed-by: Ritesh Harjani Link: https://lore.kernel.org/r/50eef383add1ea529651640574111076c55aca9f.1572949325.git.mbobrowski@mbobrowski.org Signed-off-by: Theodore Ts'o --- fs/ext4/inode.c | 113 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 61 insertions(+), 52 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9e1ac9f..b540f29 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -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) { @@ -3553,62 +3610,14 @@ 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; } + if (ret < 0) + return ret; + ext4_set_iomap(inode, iomap, &map, offset, length); if (delalloc && iomap->type == IOMAP_HOLE) iomap->type = IOMAP_DELALLOC; -- 2.7.4