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SubjectRe: [PATCH] f2fs: fix data corruption issue with hardware encryption
On 10/10, Sahitya Tummala wrote:
> Direct IO can be used in case of hardware encryption. The following
> scenario results into data corruption issue in this path -
>
> Thread A - Thread B-
> -> write file#1 in direct IO
> -> GC gets kicked in
> -> GC submitted bio on meta mapping
> for file#1, but pending completion
> -> write file#1 again with new data
> in direct IO
> -> GC bio gets completed now
> -> GC writes old data to the new
> location and thus file#1 is
> corrupted.
>
> Fix this by submitting and waiting for pending io on meta mapping
> for direct IO case in f2fs_map_blocks().
>
> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
> ---
> fs/f2fs/data.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 9ef6f1f..7b2fef0 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1028,6 +1028,12 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> map->m_pblk = ei.blk + pgofs - ei.fofs;
> map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
> map->m_flags = F2FS_MAP_MAPPED;
> + /* for HW encryption, but to avoid potential issue in future */
> + if (flag == F2FS_GET_BLOCK_DIO) {
> + blkaddr = map->m_pblk;
> + for (; blkaddr < map->m_pblk + map->m_len; blkaddr++)
> + f2fs_wait_on_block_writeback(sbi, blkaddr);

Do we need this? IIRC, DIO would give create=1.

> + }
> if (map->m_next_extent)
> *map->m_next_extent = pgofs + map->m_len;
> goto out;
> @@ -1188,6 +1194,12 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
> goto next_dnode;
>
> sync_out:
> + /* for hardware encryption, but to avoid potential issue in future */
> + if (flag == F2FS_GET_BLOCK_DIO && map->m_flags & F2FS_MAP_MAPPED) {
> + blkaddr = map->m_pblk;
> + for (; blkaddr < map->m_pblk + map->m_len; blkaddr++)
> + f2fs_wait_on_block_writeback(sbi, blkaddr);
> + }
> if (flag == F2FS_GET_BLOCK_PRECACHE) {
> if (map->m_flags & F2FS_MAP_MAPPED) {
> unsigned int ofs = start_pgofs - map->m_lblk;
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

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