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    SubjectRe: [f2fs-dev] [PATCH v4] f2fs: change fiemap way in printing compression chunk
    On 07/27, Chao Yu wrote:
    > On 2021/7/26 12:18, Daeho Jeong wrote:
    > > From: Daeho Jeong <daehojeong@google.com>
    > >
    > > When we print out a discontinuous compression chunk, it shows like a
    > > continuous chunk now. To show it more correctly, I've changed the way of
    > > printing fiemap info like below. Plus, eliminated NEW_ADDR(-1) in fiemap
    > > info, since it is not in fiemap user api manual.
    > >
    > > Let's assume 16KB compression cluster.
    > >
    > > <before>
    > > Logical Physical Length Flags
    > > 0: 0000000000000000 00000002c091f000 0000000000004000 1008
    > > 1: 0000000000004000 00000002c0920000 0000000000004000 1008
    > > ...
    > > 9: 0000000000034000 0000000f8c623000 0000000000004000 1008
    > > 10: 0000000000038000 000000101a6eb000 0000000000004000 1008
    > >
    > > <after>
    > > 0: 0000000000000000 00000002c091f000 0000000000004000 1008
    > > 1: 0000000000004000 00000002c0920000 0000000000004000 1008
    > > ...
    > > 9: 0000000000034000 0000000f8c623000 0000000000001000 1008
    > > 10: 0000000000035000 000000101a6ea000 0000000000003000 1008
    > > 11: 0000000000038000 000000101a6eb000 0000000000002000 1008
    > > 12: 000000000003a000 00000002c3544000 0000000000002000 1008
    > >
    > > Flags
    > > 0x1000 => FIEMAP_EXTENT_MERGED
    > > 0x0008 => FIEMAP_EXTENT_ENCODED
    > >
    > > Signed-off-by: Daeho Jeong <daehojeong@google.com>
    > > Tested-by: Eric Biggers <ebiggers@google.com>
    > >
    > > ---
    > > v4: initialized count_in_cluster
    > > v3: fix the missing last extent flag issue
    > > v2: changed the print format
    > > ---
    > > fs/f2fs/data.c | 75 ++++++++++++++++++++++++++++----------------------
    > > 1 file changed, 42 insertions(+), 33 deletions(-)
    > >
    > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
    > > index 3a01a1b50104..1a716c3b5457 100644
    > > --- a/fs/f2fs/data.c
    > > +++ b/fs/f2fs/data.c
    > > @@ -1843,8 +1843,9 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
    > > u64 logical = 0, phys = 0, size = 0;
    > > u32 flags = 0;
    > > int ret = 0;
    > > - bool compr_cluster = false;
    > > + bool compr_cluster = false, compr_appended;
    > > unsigned int cluster_size = F2FS_I(inode)->i_cluster_size;
    > > + unsigned int count_in_cluster = 0;
    > > loff_t maxbytes;
    > > if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
    > > @@ -1892,15 +1893,17 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
    > > map.m_next_pgofs = &next_pgofs;
    > > map.m_seg_type = NO_CHECK_TYPE;
    > > - if (compr_cluster)
    > > - map.m_len = cluster_size - 1;
    > > + if (compr_cluster) {
    > > + map.m_lblk += 1;
    > > + map.m_len = cluster_size - count_in_cluster;
    > > + }
    > > ret = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_FIEMAP);
    > > if (ret)
    > > goto out;
    > > /* HOLE */
    > > - if (!(map.m_flags & F2FS_MAP_FLAGS)) {
    > > + if (!compr_cluster && !(map.m_flags & F2FS_MAP_FLAGS)) {
    > > start_blk = next_pgofs;
    > > if (blks_to_bytes(inode, start_blk) < blks_to_bytes(inode,
    > > @@ -1910,6 +1913,14 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
    > > flags |= FIEMAP_EXTENT_LAST;
    > > }
    > > + compr_appended = false;
    > > + /* In a case of compressed cluster, append this to the last extent */
    > > + if (compr_cluster && ((map.m_flags & F2FS_MAP_UNWRITTEN) ||
    > > + !(map.m_flags & F2FS_MAP_FLAGS))) {
    > > + compr_appended = true;
    > > + goto skip_fill;
    > > + }
    > > +
    > > if (size) {
    > > flags |= FIEMAP_EXTENT_MERGED;
    > > if (IS_ENCRYPTED(inode))
    > > @@ -1926,38 +1937,36 @@ int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
    > > if (start_blk > last_blk)
    > > goto out;
    > > - if (compr_cluster) {
    > > - compr_cluster = false;
    > > -
    > > -
    > > - logical = blks_to_bytes(inode, start_blk - 1);
    > > - phys = blks_to_bytes(inode, map.m_pblk);
    > > - size = blks_to_bytes(inode, cluster_size);
    > > -
    > > - flags |= FIEMAP_EXTENT_ENCODED;
    > > -
    > > - start_blk += cluster_size - 1;
    > > -
    > > - if (start_blk > last_blk)
    > > - goto out;
    > > -
    > > - goto prep_next;
    > > - }
    > > -
    > > +skip_fill:
    > > if (map.m_pblk == COMPRESS_ADDR) {
    >
    > Looks good, but one more thing I concern is how about detecting and
    > returning -EFSCORRUPTED for below corrupted metadata cases:
    > - [COMPRESS_ADDR, blkaddr, COMPRESS_ADDR, NEW_ADDR]
    > - [blkaddr, COMPRESS_ADDR, NULL_ADDR, NULL_ADDR]

    Do we really need to catch this in fiemap? What about giving the current
    layout with warning message and setting NEED_FSCK?

    >
    > Thanks,
    >
    > > compr_cluster = true;
    > > - start_blk++;
    > > - goto prep_next;
    > > - }
    > > -
    > > - logical = blks_to_bytes(inode, start_blk);
    > > - phys = blks_to_bytes(inode, map.m_pblk);
    > > - size = blks_to_bytes(inode, map.m_len);
    > > - flags = 0;
    > > - if (map.m_flags & F2FS_MAP_UNWRITTEN)
    > > - flags = FIEMAP_EXTENT_UNWRITTEN;
    > > + count_in_cluster = 1;
    > > + } else if (compr_appended) {
    > > + unsigned int appended_blks = cluster_size -
    > > + count_in_cluster + 1;
    > > + size += blks_to_bytes(inode, appended_blks);
    > > + start_blk += appended_blks;
    > > + compr_cluster = false;
    > > + } else {
    > > + logical = blks_to_bytes(inode, start_blk);
    > > + phys = __is_valid_data_blkaddr(map.m_pblk) ?
    > > + blks_to_bytes(inode, map.m_pblk) : 0;
    > > + size = blks_to_bytes(inode, map.m_len);
    > > + flags = 0;
    > > +
    > > + if (compr_cluster) {
    > > + flags = FIEMAP_EXTENT_ENCODED;
    > > + count_in_cluster += map.m_len;
    > > + if (count_in_cluster == cluster_size) {
    > > + compr_cluster = false;
    > > + size += blks_to_bytes(inode, 1);
    > > + }
    > > + } else if (map.m_flags & F2FS_MAP_UNWRITTEN) {
    > > + flags = FIEMAP_EXTENT_UNWRITTEN;
    > > + }
    > > - start_blk += bytes_to_blks(inode, size);
    > > + start_blk += bytes_to_blks(inode, size);
    > > + }
    > > prep_next:
    > > cond_resched();
    > >

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