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ext2: annotate s_rsv_window_root as requiring s_rsv_window_lock

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The per-filesystem reservation window rb-tree (s_rsv_window_root) is
protected by s_rsv_window_lock. Mark the s_rsv_window_root field
with __guarded_by() for Clang's context analysis.

The helpers (ext2_rsv_window_add, rsv_window_remove, and
find_next_reservable_window) that mutate or walk the tree are all
called with the s_rsv_window_lock held. Annotate these helpers
with __must_hold().

The accesses in ext2_fill_super() are before the superblock is live.
Since no concurrent access should be possible, s_rsv_window_lock
is not taken. Convert the spinlock initialization to use
scoped_guard(spinlock_init, ...) and place the writes under the
guard to prevent warnings.

Signed-off-by: Timothy Day <timday@thelustrecollective.com>
Acked-by: Marco Elver <elver@google.com>
Link: https://patch.msgid.link/20260811160336.782342-8-timday@thelustrecollective.com
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Timothy Day 2026-08-11 12:03:35 -04:00 committed by Jan Kara
parent d8c906454f
commit c23746524f
3 changed files with 20 additions and 14 deletions
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3
fs/ext2/balloc.c
View File

@ -334,6 +334,7 @@ search_reserve_window(struct rb_root *root, ext2_fsblk_t goal)
*/
void ext2_rsv_window_add(struct super_block *sb,
struct ext2_reserve_window_node *rsv)
__must_hold(&EXT2_SB(sb)->s_rsv_window_lock)
{
struct rb_root *root = &EXT2_SB(sb)->s_rsv_window_root;
struct rb_node *node = &rsv->rsv_node;
@ -373,6 +374,7 @@ void ext2_rsv_window_add(struct super_block *sb,
*/
static void rsv_window_remove(struct super_block *sb,
struct ext2_reserve_window_node *rsv)
__must_hold(&EXT2_SB(sb)->s_rsv_window_lock)
{
rsv->rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
rsv->rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
@ -759,6 +761,7 @@ static int find_next_reservable_window(
struct super_block * sb,
ext2_fsblk_t start_block,
ext2_fsblk_t last_block)
__must_hold(&EXT2_SB(sb)->s_rsv_window_lock)
{
struct rb_node *next;
struct ext2_reserve_window_node *rsv, *prev;

5
fs/ext2/ext2.h
View File

@ -102,7 +102,7 @@ struct ext2_sb_info {
struct blockgroup_lock *s_blockgroup_lock;
/* root of the per fs reservation window tree */
spinlock_t s_rsv_window_lock;
struct rb_root s_rsv_window_root;
struct rb_root s_rsv_window_root __guarded_by(&s_rsv_window_lock);
struct ext2_reserve_window_node s_rsv_window_head;
/*
* s_lock protects against concurrent modifications of s_mount_state,
@ -712,7 +712,8 @@ extern void ext2_discard_reservation (struct inode *);
extern int ext2_should_retry_alloc(struct super_block *sb, int *retries);
extern void ext2_init_block_alloc_info(struct inode *inode)
__must_hold(&EXT2_I(inode)->truncate_mutex);
extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_window_node *rsv);
extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_window_node *rsv)
__must_hold(&EXT2_SB(sb)->s_rsv_window_lock);
/* dir.c */
int ext2_add_link(struct dentry *, struct inode *);

26
fs/ext2/super.c
View File

@ -1134,18 +1134,20 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
/* per filesystem reservation list head & lock */
spin_lock_init(&sbi->s_rsv_window_lock);
sbi->s_rsv_window_root = RB_ROOT;
/*
* Add a single, static dummy reservation to the start of the
* reservation window list --- it gives us a placeholder for
* append-at-start-of-list which makes the allocation logic
* _much_ simpler.
*/
sbi->s_rsv_window_head.rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
sbi->s_rsv_window_head.rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
sbi->s_rsv_window_head.rsv_alloc_hit = 0;
sbi->s_rsv_window_head.rsv_goal_size = 0;
ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);
scoped_guard(spinlock, &EXT2_SB(sb)->s_rsv_window_lock) {
sbi->s_rsv_window_root = RB_ROOT;
/*
* Add a single, static dummy reservation to the start of the
* reservation window list --- it gives us a placeholder for
* append-at-start-of-list which makes the allocation logic
* _much_ simpler.
*/
sbi->s_rsv_window_head.rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
sbi->s_rsv_window_head.rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
sbi->s_rsv_window_head.rsv_alloc_hit = 0;
sbi->s_rsv_window_head.rsv_goal_size = 0;
ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);
}
err = percpu_counter_init(&sbi->s_freeblocks_counter,
ext2_count_free_blocks(sb), GFP_KERNEL);