fs/fs-writeback.c:2397:6: warning: variable 'wb' is used uninitialized whenever 'if' condition is false
From: kernel test robot
Date: Wed May 04 2022 - 16:11:07 EST
tree: https://github.com/intel-lab-lkp/linux/commits/UPDATE-20220505-023756/Jchao-Sun/Add-assert-for-inode-i_io_list-in-inode_io_list_move_locked/20220503-180501
head: af0b042e914fbaf7a7ac9d463c91b8566461c39f
commit: af0b042e914fbaf7a7ac9d463c91b8566461c39f writeback: Fix inode->i_io_list not be protected by inode->i_lock error
date: 87 minutes ago
config: x86_64-randconfig-a011-20220502 (https://download.01.org/0day-ci/archive/20220505/202205050403.jB6rulkz-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 363b3a645a1e30011cc8da624f13dac5fd915628)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/af0b042e914fbaf7a7ac9d463c91b8566461c39f
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review UPDATE-20220505-023756/Jchao-Sun/Add-assert-for-inode-i_io_list-in-inode_io_list_move_locked/20220503-180501
git checkout af0b042e914fbaf7a7ac9d463c91b8566461c39f
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
>> fs/fs-writeback.c:2397:6: warning: variable 'wb' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if ((inode->i_state & flags) != flags) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/fs-writeback.c:2467:15: note: uninitialized use occurs here
spin_unlock(&wb->list_lock);
^~
fs/fs-writeback.c:2397:2: note: remove the 'if' if its condition is always true
if ((inode->i_state & flags) != flags) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/fs-writeback.c:2355:26: note: initialize the variable 'wb' to silence this warning
struct bdi_writeback *wb;
^
= NULL
1 warning generated.
vim +2397 fs/fs-writeback.c
1efff914afac8a Theodore Ts'o 2015-03-17 2323
03ba3782e8dcc5 Jens Axboe 2009-09-09 2324 /**
35d14f278e530e Eric Biggers 2021-01-12 2325 * __mark_inode_dirty - internal function to mark an inode dirty
0117d4272b1acd Mauro Carvalho Chehab 2017-05-12 2326 *
03ba3782e8dcc5 Jens Axboe 2009-09-09 2327 * @inode: inode to mark
35d14f278e530e Eric Biggers 2021-01-12 2328 * @flags: what kind of dirty, e.g. I_DIRTY_SYNC. This can be a combination of
35d14f278e530e Eric Biggers 2021-01-12 2329 * multiple I_DIRTY_* flags, except that I_DIRTY_TIME can't be combined
35d14f278e530e Eric Biggers 2021-01-12 2330 * with I_DIRTY_PAGES.
0117d4272b1acd Mauro Carvalho Chehab 2017-05-12 2331 *
35d14f278e530e Eric Biggers 2021-01-12 2332 * Mark an inode as dirty. We notify the filesystem, then update the inode's
35d14f278e530e Eric Biggers 2021-01-12 2333 * dirty flags. Then, if needed we add the inode to the appropriate dirty list.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2334 *
35d14f278e530e Eric Biggers 2021-01-12 2335 * Most callers should use mark_inode_dirty() or mark_inode_dirty_sync()
35d14f278e530e Eric Biggers 2021-01-12 2336 * instead of calling this directly.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2337 *
35d14f278e530e Eric Biggers 2021-01-12 2338 * CAREFUL! We only add the inode to the dirty list if it is hashed or if it
35d14f278e530e Eric Biggers 2021-01-12 2339 * refers to a blockdev. Unhashed inodes will never be added to the dirty list
35d14f278e530e Eric Biggers 2021-01-12 2340 * even if they are later hashed, as they will have been marked dirty already.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2341 *
35d14f278e530e Eric Biggers 2021-01-12 2342 * In short, ensure you hash any inodes _before_ you start marking them dirty.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2343 *
03ba3782e8dcc5 Jens Axboe 2009-09-09 2344 * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
03ba3782e8dcc5 Jens Axboe 2009-09-09 2345 * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of
03ba3782e8dcc5 Jens Axboe 2009-09-09 2346 * the kernel-internal blockdev inode represents the dirtying time of the
03ba3782e8dcc5 Jens Axboe 2009-09-09 2347 * blockdev's pages. This is why for I_DIRTY_PAGES we always use
03ba3782e8dcc5 Jens Axboe 2009-09-09 2348 * page->mapping->host, so the page-dirtying time is recorded in the internal
03ba3782e8dcc5 Jens Axboe 2009-09-09 2349 * blockdev inode.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2350 */
03ba3782e8dcc5 Jens Axboe 2009-09-09 2351 void __mark_inode_dirty(struct inode *inode, int flags)
03ba3782e8dcc5 Jens Axboe 2009-09-09 2352 {
03ba3782e8dcc5 Jens Axboe 2009-09-09 2353 struct super_block *sb = inode->i_sb;
35d14f278e530e Eric Biggers 2021-01-12 2354 int dirtytime = 0;
af0b042e914fba Jchao Sun 2022-05-04 2355 struct bdi_writeback *wb;
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2356
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2357 trace_writeback_mark_inode_dirty(inode, flags);
03ba3782e8dcc5 Jens Axboe 2009-09-09 2358
35d14f278e530e Eric Biggers 2021-01-12 2359 if (flags & I_DIRTY_INODE) {
03ba3782e8dcc5 Jens Axboe 2009-09-09 2360 /*
35d14f278e530e Eric Biggers 2021-01-12 2361 * Notify the filesystem about the inode being dirtied, so that
35d14f278e530e Eric Biggers 2021-01-12 2362 * (if needed) it can update on-disk fields and journal the
35d14f278e530e Eric Biggers 2021-01-12 2363 * inode. This is only needed when the inode itself is being
35d14f278e530e Eric Biggers 2021-01-12 2364 * dirtied now. I.e. it's only needed for I_DIRTY_INODE, not
35d14f278e530e Eric Biggers 2021-01-12 2365 * for just I_DIRTY_PAGES or I_DIRTY_TIME.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2366 */
9fb0a7da0c528d Tejun Heo 2013-01-11 2367 trace_writeback_dirty_inode_start(inode, flags);
03ba3782e8dcc5 Jens Axboe 2009-09-09 2368 if (sb->s_op->dirty_inode)
a38ed483a72672 Eric Biggers 2021-01-12 2369 sb->s_op->dirty_inode(inode, flags & I_DIRTY_INODE);
9fb0a7da0c528d Tejun Heo 2013-01-11 2370 trace_writeback_dirty_inode(inode, flags);
e2728c5621fd9c Eric Biggers 2021-01-12 2371
35d14f278e530e Eric Biggers 2021-01-12 2372 /* I_DIRTY_INODE supersedes I_DIRTY_TIME. */
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2373 flags &= ~I_DIRTY_TIME;
35d14f278e530e Eric Biggers 2021-01-12 2374 } else {
35d14f278e530e Eric Biggers 2021-01-12 2375 /*
35d14f278e530e Eric Biggers 2021-01-12 2376 * Else it's either I_DIRTY_PAGES, I_DIRTY_TIME, or nothing.
35d14f278e530e Eric Biggers 2021-01-12 2377 * (We don't support setting both I_DIRTY_PAGES and I_DIRTY_TIME
35d14f278e530e Eric Biggers 2021-01-12 2378 * in one call to __mark_inode_dirty().)
35d14f278e530e Eric Biggers 2021-01-12 2379 */
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2380 dirtytime = flags & I_DIRTY_TIME;
35d14f278e530e Eric Biggers 2021-01-12 2381 WARN_ON_ONCE(dirtytime && flags != I_DIRTY_TIME);
35d14f278e530e Eric Biggers 2021-01-12 2382 }
03ba3782e8dcc5 Jens Axboe 2009-09-09 2383
03ba3782e8dcc5 Jens Axboe 2009-09-09 2384 /*
9c6ac78eb3521c Tejun Heo 2014-10-24 2385 * Paired with smp_mb() in __writeback_single_inode() for the
9c6ac78eb3521c Tejun Heo 2014-10-24 2386 * following lockless i_state test. See there for details.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2387 */
03ba3782e8dcc5 Jens Axboe 2009-09-09 2388 smp_mb();
03ba3782e8dcc5 Jens Axboe 2009-09-09 2389
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2390 if (((inode->i_state & flags) == flags) ||
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2391 (dirtytime && (inode->i_state & I_DIRTY_INODE)))
03ba3782e8dcc5 Jens Axboe 2009-09-09 2392 return;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2393
250df6ed274d76 Dave Chinner 2011-03-22 2394 spin_lock(&inode->i_lock);
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2395 if (dirtytime && (inode->i_state & I_DIRTY_INODE))
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2396 goto out_unlock_inode;
03ba3782e8dcc5 Jens Axboe 2009-09-09 @2397 if ((inode->i_state & flags) != flags) {
03ba3782e8dcc5 Jens Axboe 2009-09-09 2398 const int was_dirty = inode->i_state & I_DIRTY;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2399
52ebea749aaed1 Tejun Heo 2015-05-22 2400 inode_attach_wb(inode, NULL);
52ebea749aaed1 Tejun Heo 2015-05-22 2401
35d14f278e530e Eric Biggers 2021-01-12 2402 /* I_DIRTY_INODE supersedes I_DIRTY_TIME. */
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2403 if (flags & I_DIRTY_INODE)
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2404 inode->i_state &= ~I_DIRTY_TIME;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2405 inode->i_state |= flags;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2406
af0b042e914fba Jchao Sun 2022-05-04 2407 wb = locked_inode_to_wb_and_lock_list(inode);
af0b042e914fba Jchao Sun 2022-05-04 2408 spin_lock(&inode->i_lock);
af0b042e914fba Jchao Sun 2022-05-04 2409
03ba3782e8dcc5 Jens Axboe 2009-09-09 2410 /*
5afced3bf28100 Jan Kara 2020-05-29 2411 * If the inode is queued for writeback by flush worker, just
5afced3bf28100 Jan Kara 2020-05-29 2412 * update its dirty state. Once the flush worker is done with
5afced3bf28100 Jan Kara 2020-05-29 2413 * the inode it will place it on the appropriate superblock
5afced3bf28100 Jan Kara 2020-05-29 2414 * list, based upon its state.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2415 */
5afced3bf28100 Jan Kara 2020-05-29 2416 if (inode->i_state & I_SYNC_QUEUED)
af0b042e914fba Jchao Sun 2022-05-04 2417 goto out_unlock;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2418
03ba3782e8dcc5 Jens Axboe 2009-09-09 2419 /*
03ba3782e8dcc5 Jens Axboe 2009-09-09 2420 * Only add valid (hashed) inodes to the superblock's
03ba3782e8dcc5 Jens Axboe 2009-09-09 2421 * dirty list. Add blockdev inodes as well.
03ba3782e8dcc5 Jens Axboe 2009-09-09 2422 */
03ba3782e8dcc5 Jens Axboe 2009-09-09 2423 if (!S_ISBLK(inode->i_mode)) {
1d3382cbf02986 Al Viro 2010-10-23 2424 if (inode_unhashed(inode))
af0b042e914fba Jchao Sun 2022-05-04 2425 goto out_unlock;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2426 }
a4ffdde6e56fdf Al Viro 2010-06-02 2427 if (inode->i_state & I_FREEING)
af0b042e914fba Jchao Sun 2022-05-04 2428 goto out_unlock;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2429
03ba3782e8dcc5 Jens Axboe 2009-09-09 2430 /*
03ba3782e8dcc5 Jens Axboe 2009-09-09 2431 * If the inode was already on b_dirty/b_io/b_more_io, don't
03ba3782e8dcc5 Jens Axboe 2009-09-09 2432 * reposition it (that would break b_dirty time-ordering).
03ba3782e8dcc5 Jens Axboe 2009-09-09 2433 */
03ba3782e8dcc5 Jens Axboe 2009-09-09 2434 if (!was_dirty) {
d6c10f1fc8626d Tejun Heo 2015-05-22 2435 struct list_head *dirty_list;
a66979abad090b Dave Chinner 2011-03-22 2436 bool wakeup_bdi = false;
500b067c5e6cee Jens Axboe 2009-09-09 2437
03ba3782e8dcc5 Jens Axboe 2009-09-09 2438 inode->dirtied_when = jiffies;
a2f4870697a5bc Theodore Ts'o 2015-03-17 2439 if (dirtytime)
a2f4870697a5bc Theodore Ts'o 2015-03-17 2440 inode->dirtied_time_when = jiffies;
d6c10f1fc8626d Tejun Heo 2015-05-22 2441
0e11f6443f522f Christoph Hellwig 2018-02-21 2442 if (inode->i_state & I_DIRTY)
0747259d13febf Tejun Heo 2015-05-22 2443 dirty_list = &wb->b_dirty;
a2f4870697a5bc Theodore Ts'o 2015-03-17 2444 else
0747259d13febf Tejun Heo 2015-05-22 2445 dirty_list = &wb->b_dirty_time;
d6c10f1fc8626d Tejun Heo 2015-05-22 2446
c7f5408493aeb0 Dave Chinner 2015-03-04 2447 wakeup_bdi = inode_io_list_move_locked(inode, wb,
d6c10f1fc8626d Tejun Heo 2015-05-22 2448 dirty_list);
d6c10f1fc8626d Tejun Heo 2015-05-22 2449
0747259d13febf Tejun Heo 2015-05-22 2450 spin_unlock(&wb->list_lock);
af0b042e914fba Jchao Sun 2022-05-04 2451 spin_unlock(&inode->i_lock);
0ae45f63d4ef8d Theodore Ts'o 2015-02-02 2452 trace_writeback_dirty_inode_enqueue(inode);
a66979abad090b Dave Chinner 2011-03-22 2453
d6c10f1fc8626d Tejun Heo 2015-05-22 2454 /*
d6c10f1fc8626d Tejun Heo 2015-05-22 2455 * If this is the first dirty inode for this bdi,
d6c10f1fc8626d Tejun Heo 2015-05-22 2456 * we have to wake-up the corresponding bdi thread
d6c10f1fc8626d Tejun Heo 2015-05-22 2457 * to make sure background write-back happens
d6c10f1fc8626d Tejun Heo 2015-05-22 2458 * later.
d6c10f1fc8626d Tejun Heo 2015-05-22 2459 */
f56753ac2a9081 Christoph Hellwig 2020-09-24 2460 if (wakeup_bdi &&
f56753ac2a9081 Christoph Hellwig 2020-09-24 2461 (wb->bdi->capabilities & BDI_CAP_WRITEBACK))
0747259d13febf Tejun Heo 2015-05-22 2462 wb_wakeup_delayed(wb);
a66979abad090b Dave Chinner 2011-03-22 2463 return;
03ba3782e8dcc5 Jens Axboe 2009-09-09 2464 }
03ba3782e8dcc5 Jens Axboe 2009-09-09 2465 }
af0b042e914fba Jchao Sun 2022-05-04 2466 out_unlock:
af0b042e914fba Jchao Sun 2022-05-04 2467 spin_unlock(&wb->list_lock);
250df6ed274d76 Dave Chinner 2011-03-22 2468 out_unlock_inode:
250df6ed274d76 Dave Chinner 2011-03-22 2469 spin_unlock(&inode->i_lock);
03ba3782e8dcc5 Jens Axboe 2009-09-09 2470 }
03ba3782e8dcc5 Jens Axboe 2009-09-09 2471 EXPORT_SYMBOL(__mark_inode_dirty);
03ba3782e8dcc5 Jens Axboe 2009-09-09 2472
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