fs/ext4/balloc.c

Source file repositories/reference/linux-study-clean/fs/ext4/balloc.c

File Facts

System
Linux kernel
Corpus path
fs/ext4/balloc.c
Extension
.c
Size
29718 bytes
Lines
1004
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

ext4_simulate_fail(sb, EXT4_SIM_BBITMAP_CRC))) {
		ext4_unlock_group(sb, block_group);
		ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
		ext4_mark_group_bitmap_corrupted(sb, block_group,
					EXT4_GROUP_INFO_BBITMAP_CORRUPT);
		return -EFSBADCRC;
	}
	blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
	if (unlikely(blk != 0)) {
		ext4_unlock_group(sb, block_group);
		ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
			   block_group, blk);
		ext4_mark_group_bitmap_corrupted(sb, block_group,
					EXT4_GROUP_INFO_BBITMAP_CORRUPT);
		return -EFSCORRUPTED;
	}
	blk = ext4_valid_block_bitmap_padding(sb, block_group, bh);
	if (unlikely(blk != 0)) {
		ext4_unlock_group(sb, block_group);
		ext4_error(sb, "bg %u: block %llu: padding at end of block bitmap is not set",
			   block_group, blk);
		ext4_mark_group_bitmap_corrupted(sb, block_group,
						 EXT4_GROUP_INFO_BBITMAP_CORRUPT);
		return -EFSCORRUPTED;
	}
	set_buffer_verified(bh);
verified:
	ext4_unlock_group(sb, block_group);
	return 0;
}

/**
 * ext4_read_block_bitmap_nowait()
 * @sb:			super block
 * @block_group:	given block group
 * @ignore_locked:	ignore locked buffers
 *
 * Read the bitmap for a given block_group,and validate the
 * bits for block/inode/inode tables are set in the bitmaps
 *
 * Return buffer_head on success or an ERR_PTR in case of failure.
 */
struct buffer_head *
ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group,
			      bool ignore_locked)
{
	struct ext4_group_desc *desc;
	struct ext4_sb_info *sbi = EXT4_SB(sb);
	struct buffer_head *bh;
	ext4_fsblk_t bitmap_blk;
	int err;

	KUNIT_STATIC_STUB_REDIRECT(ext4_read_block_bitmap_nowait,
				   sb, block_group, ignore_locked);

	desc = ext4_get_group_desc(sb, block_group, NULL);
	if (!desc)
		return ERR_PTR(-EFSCORRUPTED);
	bitmap_blk = ext4_block_bitmap(sb, desc);
	if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
	    (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
		ext4_error(sb, "Invalid block bitmap block %llu in "
			   "block_group %u", bitmap_blk, block_group);
		ext4_mark_group_bitmap_corrupted(sb, block_group,
					EXT4_GROUP_INFO_BBITMAP_CORRUPT);
		return ERR_PTR(-EFSCORRUPTED);
	}
	bh = sb_getblk(sb, bitmap_blk);
	if (unlikely(!bh)) {
		ext4_warning(sb, "Cannot get buffer for block bitmap - "
			     "block_group = %u, block_bitmap = %llu",
			     block_group, bitmap_blk);
		return ERR_PTR(-ENOMEM);
	}

	if (ignore_locked && buffer_locked(bh)) {
		/* buffer under IO already, return if called for prefetching */
		put_bh(bh);
		return NULL;
	}

	if (bitmap_uptodate(bh))
		goto verify;

	lock_buffer(bh);
	if (bitmap_uptodate(bh)) {
		unlock_buffer(bh);
		goto verify;
	}
	ext4_lock_group(sb, block_group);

Annotation

Implementation Notes