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btrfs-progs: check: Populate extent generation correctly for data extents

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[BUG]
When using `btrfs check --init-extent-tree`, we will create incorrect
generation number for data extents in extent tree:

        item 10 key (13631488 EXTENT_ITEM 1048576) itemoff 15828 itemsize 53
                refs 1 gen 0 flags DATA
                extent data backref root FS_TREE objectid 257 offset 0 count 1

[CAUSE]
Since data extent generation is not as obvious as tree blocks, which has
header containing its generations, so for data extents, its
extent_record::generation is not really updated, resulting such 0
generation.

[FIX]
To get generation of a data extent, there are two sources we can rely:
- EXTENT_ITEM
  There is always a btrfs_extent_item::generation can be utilized.
  Although this is not possible for --init-extent-tree use case.

- EXTENT_DATA
  We have btrfs_file_extent_item::generation for regular and
  preallocated data extents.
  Since --init-extent-tree will go through subvolume trees, this would
  be the main source for extent data generation.

Then we only need to make add_data_backref() to accept @gen parameter,
and pass it down to extent_record structure.

And for the final extent item generation update, here we add extra
fallback values, if we can't find FILE_EXTENT items.
In that case, we just fall back to current transid.

With this modification, recreated data EXTENT_ITEM now has correct
generation number:

        item 10 key (13631488 EXTENT_ITEM 1048576) itemoff 15828 itemsize 53
                refs 1 gen 6 flags DATA
                extent data backref root FS_TREE objectid 257 offset 0 count 1

Reviewed-by: Su Yue <Damenly_Su@gmx.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2019-12-31 15:12:17 +08:00 committed by David Sterba
parent 9a85b7db02
commit 8d45dc270a
1 changed files with 17 additions and 7 deletions
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24
check/main.c
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@ -4810,7 +4810,7 @@ static int add_tree_backref(struct cache_tree *extent_cache, u64 bytenr,
static int add_data_backref(struct cache_tree *extent_cache, u64 bytenr,
u64 parent, u64 root, u64 owner, u64 offset,
u32 num_refs, int found_ref, u64 max_size)
u32 num_refs, u64 gen, int found_ref, u64 max_size)
{
struct extent_record *rec;
struct data_backref *back;
@ -4826,6 +4826,7 @@ static int add_data_backref(struct cache_tree *extent_cache, u64 bytenr,
tmpl.start = bytenr;
tmpl.nr = 1;
tmpl.max_size = max_size;
tmpl.generation = gen;
ret = add_extent_rec_nolookup(extent_cache, &tmpl);
if (ret)
@ -4840,6 +4841,8 @@ static int add_data_backref(struct cache_tree *extent_cache, u64 bytenr,
if (rec->max_size < max_size)
rec->max_size = max_size;
if (rec->generation < gen)
rec->generation = gen;
/*
* If found_ref is set then max_size is the real size and must match the
* existing refs. So if we have already found a ref then we need to
@ -5315,6 +5318,7 @@ static int process_extent_item(struct btrfs_root *root,
u64 refs = 0;
u64 offset;
u64 num_bytes;
u64 gen;
int metadata = 0;
btrfs_item_key_to_cpu(eb, &key, slot);
@ -5340,6 +5344,7 @@ static int process_extent_item(struct btrfs_root *root,
ei = btrfs_item_ptr(eb, slot, struct btrfs_extent_item);
refs = btrfs_extent_refs(eb, ei);
gen = btrfs_extent_generation(eb, ei);
if (btrfs_extent_flags(eb, ei) & BTRFS_EXTENT_FLAG_TREE_BLOCK)
metadata = 1;
else
@ -5362,6 +5367,7 @@ static int process_extent_item(struct btrfs_root *root,
tmpl.metadata = metadata;
tmpl.found_rec = 1;
tmpl.max_size = num_bytes;
tmpl.generation = gen;
add_extent_rec(extent_cache, &tmpl);
ptr = (unsigned long)(ei + 1);
@ -5401,14 +5407,14 @@ static int process_extent_item(struct btrfs_root *root,
dref),
btrfs_extent_data_ref_offset(eb, dref),
btrfs_extent_data_ref_count(eb, dref),
0, num_bytes);
gen, 0, num_bytes);
break;
case BTRFS_SHARED_DATA_REF_KEY:
sref = (struct btrfs_shared_data_ref *)(iref + 1);
add_data_backref(extent_cache, key.objectid, offset,
0, 0, 0,
btrfs_shared_data_ref_count(eb, sref),
0, num_bytes);
gen, 0, num_bytes);
break;
default:
fprintf(stderr,
@ -6355,7 +6361,7 @@ static int run_next_block(struct btrfs_root *root,
ref),
btrfs_extent_data_ref_offset(buf, ref),
btrfs_extent_data_ref_count(buf, ref),
0, root->fs_info->sectorsize);
0, 0, root->fs_info->sectorsize);
continue;
}
if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
@ -6366,7 +6372,7 @@ static int run_next_block(struct btrfs_root *root,
add_data_backref(extent_cache,
key.objectid, key.offset, 0, 0, 0,
btrfs_shared_data_ref_count(buf, ref),
0, root->fs_info->sectorsize);
0, 0, root->fs_info->sectorsize);
continue;
}
if (key.type == BTRFS_ORPHAN_ITEM_KEY) {
@ -6433,7 +6439,8 @@ static int run_next_block(struct btrfs_root *root,
add_data_backref(extent_cache,
btrfs_file_extent_disk_bytenr(buf, fi),
parent, owner, key.objectid, key.offset -
btrfs_file_extent_offset(buf, fi), 1, 1,
btrfs_file_extent_offset(buf, fi), 1,
btrfs_file_extent_generation(buf, fi), 1,
btrfs_file_extent_disk_num_bytes(buf, fi));
}
} else {
@ -6736,7 +6743,10 @@ static int record_extent(struct btrfs_trans_handle *trans,
struct btrfs_extent_item);
btrfs_set_extent_refs(leaf, ei, 0);
btrfs_set_extent_generation(leaf, ei, rec->generation);
if (rec->generation)
btrfs_set_extent_generation(leaf, ei, rec->generation);
else
btrfs_set_extent_generation(leaf, ei, trans->transid);
if (back->is_data) {
btrfs_set_extent_flags(leaf, ei,