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[bugfix] do not reuse an out-of-range last allocated block hint #11

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[bugfix] do not reuse an out-of-range last allocated block hint #11

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20 changes: 16 additions & 4 deletions lib/ext2fs/alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -202,7 +202,11 @@ errcode_t ext2fs_new_block3(ext2_filsys fs, blk64_t goal,

ext2fs_clear_block_uninit(fs, ext2fs_group_of_blk2(fs, b));
*ret = b;
fs->reserved[3] = (__u32)b; // not 64-bit safe
/* reserved[] is 32 bits wide; drop a hint that would be truncated */
if (b <= 0xFFFFFFFFULL)
fs->reserved[3] = (__u32) b;
else
fs->reserved[3] = 0;
return 0;
}

Expand Down Expand Up @@ -445,8 +449,7 @@ errcode_t ext2fs_new_range(ext2_filsys fs, int flags, blk64_t goal,
if (!map)
return EXT2_ET_NO_BLOCK_BITMAP;
if (!goal || goal >= ext2fs_blocks_count(fs->super))
goal = fs->reserved[3];
// goal = fs->super->s_first_data_block;
goal = fs->reserved[3] ? fs->reserved[3] : fs->super->s_first_data_block;

start = goal;
while (!looped || start <= goal) {
Expand Down Expand Up @@ -493,7 +496,16 @@ errcode_t ext2fs_new_range(ext2_filsys fs, int flags, blk64_t goal,
b += fs->super->s_blocks_per_group)
ext2fs_clear_block_uninit(fs,
ext2fs_group_of_blk2(fs, b));
fs->reserved[3] = (__u32) end;
/*
* Only keep a hint which can still be used as a
* search start: reserved[] is 32 bits wide, so a
* larger value would be truncated into an unrelated
* block number.
*/
if (end < ext2fs_blocks_count(fs->super) && end <= 0xFFFFFFFFULL)
fs->reserved[3] = (__u32) end;
else
fs->reserved[3] = 0;
return 0;
}

Expand Down
7 changes: 6 additions & 1 deletion lib/ext2fs/fallocate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -695,7 +695,12 @@ static errcode_t extent_fallocate(ext2_filsys fs, int flags, ext2_ino_t ino,
if (err == EXT2_ET_NO_CURRENT_NODE) {
blk64_t max_blocks = ext2fs_blocks_count(fs->super);

goal = fs->reserved[3];
/*
* Only follow the hint while it still points inside the file
* system, so that the ~0ULL goal sentinel keeps working.
*/
if (fs->reserved[3] && fs->reserved[3] < max_blocks)
goal = fs->reserved[3];
if (goal == ~0ULL)
goal = ext2fs_find_inode_goal(fs, ino, inode, start);
err = ext2fs_find_first_zero_block_bitmap2(fs->block_map,
Expand Down
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