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| author | Wenjie Qi <qwjhust@gmail.com> | 2026-08-04 09:48:48 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2026-08-05 01:30:45 +0000 |
| commit | 5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f (patch) | |
| tree | 6f2af3ab37ad23dc5a78f8ca03d9cf777dab8e98 | |
| parent | 3de6b80941152a384ee1b9cf88ac1c9dd4eec6dd (diff) | |
| download | linux-5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f.tar.gz linux-5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f.zip | |
f2fs: avoid NULL checkpoint thread access in sysfs
checkpoint_merge can be enabled even when no checkpoint merge thread is
running. A read-only mount is one case: f2fs does not start
f2fs_issue_ckpt there, but ckpt_thread_ioprio is still writable through
sysfs.
The ckpt_thread_ioprio store path updates the saved ioprio value and,
when checkpoint_merge is enabled, calls set_task_ioprio() for the
checkpoint thread. If cprc->f2fs_issue_ckpt is NULL, that dereferences a
NULL task pointer.
Protect ckpt_thread_ioprio sysfs writes with s_umount as well, so the
checkpoint thread cannot disappear under the store path while updating
its ioprio.
Fixes: e65920661708 ("f2fs: add ckpt_thread_ioprio sysfs node")
Cc: stable@kernel.org
Signed-off-by: Wenjie Qi <qiwenjie@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
| -rw-r--r-- | fs/f2fs/sysfs.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index d9f81edca04a..c976549ff1bc 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -557,7 +557,7 @@ out: return -EINVAL; cprc->ckpt_thread_ioprio = IOPRIO_PRIO_VALUE(class, level); - if (test_opt(sbi, MERGE_CHECKPOINT)) { + if (cprc->f2fs_issue_ckpt) { ret = set_task_ioprio(cprc->f2fs_issue_ckpt, cprc->ckpt_thread_ioprio); if (ret) @@ -1007,13 +1007,14 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, ssize_t ret; bool gc_entry = (!strcmp(a->attr.name, "gc_urgent") || a->struct_type == GC_THREAD); + bool thread_entry = !strcmp(a->attr.name, "ckpt_thread_ioprio"); - if (gc_entry) { + if (gc_entry || thread_entry) { if (!down_read_trylock(&sbi->sb->s_umount)) return -EAGAIN; } ret = __sbi_store(a, sbi, buf, count); - if (gc_entry) + if (gc_entry || thread_entry) up_read(&sbi->sb->s_umount); return ret; |