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Merge pull request #128 from versity/zab/prealloc_fragmentation

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Zab/prealloc fragmentation
This commit is contained in:
Zach Brown
2023-06-29 09:57:32 -07:00
committed by GitHub
parent 49fe89741d 847916860d
commit a9da27444f
3 changed files with 445 additions and 8 deletions
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kmod/src/data.c
+29 -8
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@@ -456,11 +456,13 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
} else {
/*
* Preallocation of aligned regions only preallocates if
* the aligned region contains no extents at all. This
* could be fooled by offline sparse extents but we
* don't want to iterate over all offline extents in the
* aligned region.
* Preallocation within aligned regions tries to
* allocate an extent to fill the hole in the region
* that contains iblock. We search for a next extent
* from the start of the region. If it's at the start
* we might have to search again to find an existing
* extent at the end of the region. (This next could be
* given to us by the caller).
*/
div64_u64_rem(iblock, opts.data_prealloc_blocks, &rem);
start = iblock - rem;
@@ -468,8 +470,20 @@ static int alloc_block(struct super_block *sb, struct inode *inode,
ret = scoutfs_ext_next(sb, &data_ext_ops, &args, start, 1, &found);
if (ret < 0 && ret != -ENOENT)
goto out;
if (found.len && found.start < start + count)
count = 1;
/* trim count if there's an extent in the region before iblock */
if (found.len && found.start < iblock) {
count -= (found.start + found.len) - start;
start = found.start + found.len;
/* see if there's also an extent after iblock */
ret = scoutfs_ext_next(sb, &data_ext_ops, &args, iblock, 1, &found);
if (ret < 0 && ret != -ENOENT)
goto out;
}
/* trim count by a next extent in the region */
if (found.len && found.start > start && found.start < start + count)
count = (found.start - start);
}
/* overall prealloc limit */
@@ -1253,6 +1267,7 @@ int scoutfs_data_move_blocks(struct inode *from, u64 from_off,
from_iblock = from_off >> SCOUTFS_BLOCK_SM_SHIFT;
count = (byte_len + SCOUTFS_BLOCK_SM_MASK) >> SCOUTFS_BLOCK_SM_SHIFT;
to_iblock = to_off >> SCOUTFS_BLOCK_SM_SHIFT;
from_start = from_iblock;
/* only move extent blocks inside i_size, careful not to wrap */
from_size = i_size_read(from);
@@ -1329,7 +1344,7 @@ int scoutfs_data_move_blocks(struct inode *from, u64 from_off,
/* find the next extent to move */
ret = scoutfs_ext_next(sb, &data_ext_ops, &from_args,
from_iblock, 1, &ext);
from_start, 1, &ext);
if (ret < 0) {
if (ret == -ENOENT) {
done = true;
@@ -1417,6 +1432,12 @@ int scoutfs_data_move_blocks(struct inode *from, u64 from_off,
i_size_read(from);
i_size_write(to, to_size);
}
/* find next after moved extent, avoiding wrapping */
if (from_start + len < from_start)
from_start = from_iblock + count + 1;
else
from_start += len;
}