Unverified Commit 0f5bb0cf authored by David Laight's avatar David Laight Committed by Christian Brauner
Browse files

fs: use min() or umin() instead of min_t() 



min_t(unsigned int, a, b) casts an 'unsigned long' to 'unsigned int'.
Use min(a, b) instead as it promotes any 'unsigned int' to 'unsigned long'
and so cannot discard significant bits.

A couple of places need umin() because of loops like:
	nfolios = DIV_ROUND_UP(ret + start, PAGE_SIZE);

	for (i = 0; i < nfolios; i++) {
		struct folio *folio = page_folio(pages[i]);
		...
		unsigned int len = umin(ret, PAGE_SIZE - start);
		...
		ret -= len;
		...
	}
where the compiler doesn't track things well enough to know that
'ret' is never negative.

The alternate loop:
        for (i = 0; ret > 0; i++) {
                struct folio *folio = page_folio(pages[i]);
                ...
                unsigned int len = min(ret, PAGE_SIZE - start);
                ...
                ret -= len;
                ...
        }
would be equivalent and doesn't need 'nfolios'.

Most of the 'unsigned long' actually come from PAGE_SIZE.

Detected by an extra check added to min_t().

Signed-off-by: default avatarDavid Laight <david.laight.linux@gmail.com>
Link: https://patch.msgid.link/20251119224140.8616-31-david.laight.linux@gmail.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 8f0b4cce

fs/buffer.c

+1 −1
Original line number Diff line number Diff line
@@ -2354,7 +2354,7 @@ bool block_is_partially_uptodate(struct folio *folio, size_t from, size_t count) 
	if (!head)

		return false;

	blocksize = head->b_size;

	to = min_t(unsigned, folio_size(folio) - from, count);

	to = min(folio_size(folio) - from, count);

	to = from + to;

	if (from < blocksize && to > folio_size(folio) - blocksize)

		return false;

fs/exec.c

+1 −1
Original line number Diff line number Diff line
@@ -555,7 +555,7 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) 
		return -E2BIG;



	while (len > 0) {

		unsigned int bytes_to_copy = min_t(unsigned int, len,

		unsigned int bytes_to_copy = min(len,

				min_not_zero(offset_in_page(pos), PAGE_SIZE));

		struct page *page;

fs/ext4/mballoc.c

+1 −2
Original line number Diff line number Diff line
@@ -4276,8 +4276,7 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block, 
		 * get the corresponding group metadata to work with.

		 * For this we have goto again loop.

		 */

		thisgrp_len = min_t(unsigned int, (unsigned int)len,

			EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff));

		thisgrp_len = min(len, EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff));

		clen = EXT4_NUM_B2C(sbi, thisgrp_len);



		if (!ext4_sb_block_valid(sb, NULL, block, thisgrp_len)) {

fs/ext4/resize.c

+1 −1
Original line number Diff line number Diff line
@@ -1479,7 +1479,7 @@ static void ext4_update_super(struct super_block *sb, 


	/* Update the global fs size fields */

	sbi->s_groups_count += flex_gd->count;

	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,

	sbi->s_blockfile_groups = min(sbi->s_groups_count,

			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));



	/* Update the reserved block counts only once the new group is

fs/ext4/super.c

+1 −1
Original line number Diff line number Diff line
@@ -4832,7 +4832,7 @@ static int ext4_check_geometry(struct super_block *sb, 
		return -EINVAL;

	}

	sbi->s_groups_count = blocks_count;

	sbi->s_blockfile_groups = min_t(ext4_group_t, sbi->s_groups_count,

	sbi->s_blockfile_groups = min(sbi->s_groups_count,

			(EXT4_MAX_BLOCK_FILE_PHYS / EXT4_BLOCKS_PER_GROUP(sb)));

	if (((u64)sbi->s_groups_count * sbi->s_inodes_per_group) !=

	    le32_to_cpu(es->s_inodes_count)) {