[PATCH v4 00/13] Some bugfixs for ubi/ubifs

[PATCH v4 00/13] Some bugfixs for ubi/ubifs

[Zhihao Cheng]

v1->v2:
  1. Add new fix for ubifs, "ubifs: Fix to add refcount once page is set
  private"
  2. Update "ubifs: Rename whiteout atomically":
     1) Move inode mode in create_whiteout()
     2) Don't check O_SYNC for whiteout, because it inherits from the old_dir
     3) Remove useless 'synced_i_size ' assignment for whiteout, because
	it's always be zero.
     4) Remove unused variable 'ui' in create_whiteout()
  3. Update "ubifs: setflags: Make dirtied_ino_d 8 bytes aligned":
     1) Align dirtied_ino_d with 8 bytes.

v2->v3:
  1. Update "ubifs: Rename whiteout atomically":
     1) Fix misspelling 'have already check the old dir inode' ->
        'have already checked the old dir inode'
     2) Fix misspelling "Whiteout don't have non-zero size" ->
        "Whiteout  have non-zero size"
  2. Update "ubifs: Fix to add refcount once page is set private"
     1) Fix commit message to explain the root cause.
  3. Update "ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when
     fm->used_blocks>=2"
     1) Add fastmap used pebs into 'ai' in for-loop, rather than in
        two-steps(Add pebs [pnum<UBI_FM_MAX_START] then add pebs
	[pnum>=UBI_FM_MAX_START] into 'ai').

v3->v4:
  1. Update "ubifs: Add missing iput if do_tmpfile() failed in rename whiteout":
     1) Move whiteout cleanup into do_tmpfile() according to Sascha's advice
  2. Add new fix for ubifs, "ubifs: ubifs_writepage: Mark page dirty after
     writing inode failed"

Zhihao Cheng (13):
  ubifs: rename_whiteout: Fix double free for whiteout_ui->data
  ubifs: Fix deadlock in concurrent rename whiteout and inode writeback
  ubifs: Fix wrong number of inodes locked by ui_mutex in ubifs_inode
    comment
  ubifs: Add missing iput if do_tmpfile() failed in rename whiteout
  ubifs: Rename whiteout atomically
  ubifs: Fix 'ui->dirty' race between do_tmpfile() and writeback work
  ubifs: Rectify space amount budget for mkdir/tmpfile operations
  ubifs: setflags: Make dirtied_ino_d 8 bytes aligned
  ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()
  ubifs: Fix to add refcount once page is set private
  ubi: fastmap: Return error code if memory allocation fails in
    add_aeb()
  ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when
    fm->used_blocks>=2
  ubifs: ubifs_writepage: Mark page dirty after writing inode failed

 drivers/mtd/ubi/fastmap.c |  63 ++++------
 fs/ubifs/dir.c            | 235 +++++++++++++++++++++++---------------
 fs/ubifs/file.c           |  26 +++--
 fs/ubifs/io.c             |  34 +++++-
 fs/ubifs/ioctl.c          |   2 +-
 fs/ubifs/journal.c        |  52 +++++++--
 fs/ubifs/ubifs.h          |   2 +-
 7 files changed, 258 insertions(+), 156 deletions(-)

-- 
2.31.1

[PATCH v4 01/13] ubifs: rename_whiteout: Fix double free for whiteout_ui->data

[Zhihao Cheng]

'whiteout_ui->data' will be freed twice if space budget fail for
rename whiteout operation as following process:

rename_whiteout
  dev = kmalloc
  whiteout_ui->data = dev
  kfree(whiteout_ui->data)  // Free first time
  iput(whiteout)
    ubifs_free_inode
      kfree(ui->data)	    // Double free!

KASAN reports:
==================================================================
BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70
Call Trace:
  kfree+0x117/0x490
  ubifs_free_inode+0x4f/0x70 [ubifs]
  i_callback+0x30/0x60
  rcu_do_batch+0x366/0xac0
  __do_softirq+0x133/0x57f

Allocated by task 1506:
  kmem_cache_alloc_trace+0x3c2/0x7a0
  do_rename+0x9b7/0x1150 [ubifs]
  ubifs_rename+0x106/0x1f0 [ubifs]
  do_syscall_64+0x35/0x80

Freed by task 1506:
  kfree+0x117/0x490
  do_rename.cold+0x53/0x8a [ubifs]
  ubifs_rename+0x106/0x1f0 [ubifs]
  do_syscall_64+0x35/0x80

The buggy address belongs to the object at ffff88810238bed8 which
belongs to the cache kmalloc-8 of size 8
==================================================================

Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused
assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode()
-> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it
(because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release',
 and the nlink of whiteout inode is 0).

Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/dir.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 7c61d0ec0159..cfa8881d8cca 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1425,8 +1425,6 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 		err = ubifs_budget_space(c, &wht_req);
 		if (err) {
-			kfree(whiteout_ui->data);
-			whiteout_ui->data_len = 0;
 			iput(whiteout);
 			goto out_release;
 		}
-- 
2.31.1

[PATCH v4 02/13] ubifs: Fix deadlock in concurrent rename whiteout and inode writeback

[Zhihao Cheng]

Following hung tasks:
[   77.028764] task:kworker/u8:4    state:D stack:    0 pid:  132
[   77.028820] Call Trace:
[   77.029027]  schedule+0x8c/0x1b0
[   77.029067]  mutex_lock+0x50/0x60
[   77.029074]  ubifs_write_inode+0x68/0x1f0 [ubifs]
[   77.029117]  __writeback_single_inode+0x43c/0x570
[   77.029128]  writeback_sb_inodes+0x259/0x740
[   77.029148]  wb_writeback+0x107/0x4d0
[   77.029163]  wb_workfn+0x162/0x7b0

[   92.390442] task:aa              state:D stack:    0 pid: 1506
[   92.390448] Call Trace:
[   92.390458]  schedule+0x8c/0x1b0
[   92.390461]  wb_wait_for_completion+0x82/0xd0
[   92.390469]  __writeback_inodes_sb_nr+0xb2/0x110
[   92.390472]  writeback_inodes_sb_nr+0x14/0x20
[   92.390476]  ubifs_budget_space+0x705/0xdd0 [ubifs]
[   92.390503]  do_rename.cold+0x7f/0x187 [ubifs]
[   92.390549]  ubifs_rename+0x8b/0x180 [ubifs]
[   92.390571]  vfs_rename+0xdb2/0x1170
[   92.390580]  do_renameat2+0x554/0x770

, are caused by concurrent rename whiteout and inode writeback processes:
	rename_whiteout(Thread 1)	        wb_workfn(Thread2)
ubifs_rename
  do_rename
    lock_4_inodes (Hold ui_mutex)
    ubifs_budget_space
      make_free_space
        shrink_liability
	  __writeback_inodes_sb_nr
	    bdi_split_work_to_wbs (Queue new wb work)
					      wb_do_writeback(wb work)
						__writeback_single_inode
					          ubifs_write_inode
					            LOCK(ui_mutex)
							   ↑
	      wb_wait_for_completion (Wait wb work) <-- deadlock!

Reproducer (Detail program in [Link]):
  1. SYS_renameat2("/mp/dir/file", "/mp/dir/whiteout", RENAME_WHITEOUT)
  2. Consume out of space before kernel(mdelay) doing budget for whiteout

Fix it by doing whiteout space budget before locking ubifs inodes.
BTW, it also fixes wrong goto tag 'out_release' in whiteout budget
error handling path(It should at least recover dir i_size and unlock
4 ubifs inodes).

Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214733
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/dir.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index cfa8881d8cca..2735ad1affed 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -1324,6 +1324,7 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	if (flags & RENAME_WHITEOUT) {
 		union ubifs_dev_desc *dev = NULL;
+		struct ubifs_budget_req wht_req;
 
 		dev = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
 		if (!dev) {
@@ -1345,6 +1346,20 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 		whiteout_ui->data = dev;
 		whiteout_ui->data_len = ubifs_encode_dev(dev, MKDEV(0, 0));
 		ubifs_assert(c, !whiteout_ui->dirty);
+
+		memset(&wht_req, 0, sizeof(struct ubifs_budget_req));
+		wht_req.dirtied_ino = 1;
+		wht_req.dirtied_ino_d = ALIGN(whiteout_ui->data_len, 8);
+		/*
+		 * To avoid deadlock between space budget (holds ui_mutex and
+		 * waits wb work) and writeback work(waits ui_mutex), do space
+		 * budget before ubifs inodes locked.
+		 */
+		err = ubifs_budget_space(c, &wht_req);
+		if (err) {
+			iput(whiteout);
+			goto out_release;
+		}
 	}
 
 	lock_4_inodes(old_dir, new_dir, new_inode, whiteout);
@@ -1419,16 +1434,6 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 	}
 
 	if (whiteout) {
-		struct ubifs_budget_req wht_req = { .dirtied_ino = 1,
-				.dirtied_ino_d = \
-				ALIGN(ubifs_inode(whiteout)->data_len, 8) };
-
-		err = ubifs_budget_space(c, &wht_req);
-		if (err) {
-			iput(whiteout);
-			goto out_release;
-		}
-
 		inc_nlink(whiteout);
 		mark_inode_dirty(whiteout);
 
-- 
2.31.1

[PATCH v4 03/13] ubifs: Fix wrong number of inodes locked by ui_mutex in ubifs_inode comment

[Zhihao Cheng]

Since 9ec64962afb1702f75b("ubifs: Implement RENAME_EXCHANGE") and
9e0a1fff8db56eaaebb("ubifs: Implement RENAME_WHITEOUT") are applied,
ubifs_rename locks and changes 4 ubifs inodes, correct the comment
for ui_mutex in ubifs_inode.

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/ubifs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index c38066ce9ab0..972e41daff01 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -372,7 +372,7 @@ struct ubifs_gced_idx_leb {
  * @ui_mutex exists for two main reasons. At first it prevents inodes from
  * being written back while UBIFS changing them, being in the middle of an VFS
  * operation. This way UBIFS makes sure the inode fields are consistent. For
- * example, in 'ubifs_rename()' we change 3 inodes simultaneously, and
+ * example, in 'ubifs_rename()' we change 4 inodes simultaneously, and
  * write-back must not write any of them before we have finished.
  *
  * The second reason is budgeting - UBIFS has to budget all operations. If an
-- 
2.31.1

[PATCH v4 04/13] ubifs: Add missing iput if do_tmpfile() failed in rename whiteout

[Zhihao Cheng]

whiteout inode should be put when do_tmpfile() failed if inode has been
initialized. Otherwise we will get following warning during umount:
  UBIFS error (ubi0:0 pid 1494): ubifs_assert_failed [ubifs]: UBIFS
  assert failed: c->bi.dd_growth == 0, in fs/ubifs/super.c:1930
  VFS: Busy inodes after unmount of ubifs. Self-destruct in 5 seconds.

Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Suggested-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 fs/ubifs/dir.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 2735ad1affed..2cbc5f05f671 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -432,6 +432,8 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 	make_bad_inode(inode);
 	if (!instantiated)
 		iput(inode);
+	else if (whiteout)
+		iput(*whiteout);
 out_budg:
 	ubifs_release_budget(c, &req);
 	if (!instantiated)
-- 
2.31.1

[PATCH v4 05/13] ubifs: Rename whiteout atomically

[Zhihao Cheng]

Currently, rename whiteout has 3 steps:
  1. create tmpfile(which associates old dentry to tmpfile inode) for
     whiteout, and store tmpfile to disk
  2. link whiteout, associate whiteout inode to old dentry agagin and
     store old dentry, old inode, new dentry on disk
  3. writeback dirty whiteout inode to disk

Suddenly power-cut or error occurring(eg. ENOSPC returned by budget,
memory allocation failure) during above steps may cause kinds of problems:
  Problem 1: ENOSPC returned by whiteout space budget (before step 2),
	     old dentry will disappear after rename syscall, whiteout file
	     cannot be found either.

	     ls dir  // we get file, whiteout
	     rename(dir/file, dir/whiteout, REANME_WHITEOUT)
	     ENOSPC = ubifs_budget_space(&wht_req) // return
	     ls dir  // empty (no file, no whiteout)
  Problem 2: Power-cut happens before step 3, whiteout inode with 'nlink=1'
	     is not stored on disk, whiteout dentry(old dentry) is written
	     on disk, whiteout file is lost on next mount (We get "dead
	     directory entry" after executing 'ls -l' on whiteout file).

Now, we use following 3 steps to finish rename whiteout:
  1. create an in-mem inode with 'nlink = 1' as whiteout
  2. ubifs_jnl_rename (Write on disk to finish associating old dentry to
     whiteout inode, associating new dentry with old inode)
  3. iput(whiteout)

Rely writing in-mem inode on disk by ubifs_jnl_rename() to finish rename
whiteout, which avoids middle disk state caused by suddenly power-cut
and error occurring.

Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/dir.c     | 144 +++++++++++++++++++++++++++++----------------
 fs/ubifs/journal.c |  52 +++++++++++++---
 2 files changed, 136 insertions(+), 60 deletions(-)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 2cbc5f05f671..deaf2d5dba5b 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -349,8 +349,56 @@ static int ubifs_create(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
-static int do_tmpfile(struct inode *dir, struct dentry *dentry,
-		      umode_t mode, struct inode **whiteout)
+static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
+{
+	int err;
+	umode_t mode = S_IFCHR | WHITEOUT_MODE;
+	struct inode *inode;
+	struct ubifs_info *c = dir->i_sb->s_fs_info;
+	struct fscrypt_name nm;
+
+	/*
+	 * Create an inode('nlink = 1') for whiteout without updating journal,
+	 * let ubifs_jnl_rename() store it on flash to complete rename whiteout
+	 * atomically.
+	 */
+
+	dbg_gen("dent '%pd', mode %#hx in dir ino %lu",
+		dentry, mode, dir->i_ino);
+
+	err = fscrypt_setup_filename(dir, &dentry->d_name, 0, &nm);
+	if (err)
+		return ERR_PTR(err);
+
+	inode = ubifs_new_inode(c, dir, mode);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		goto out_free;
+	}
+
+	init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
+	ubifs_assert(c, inode->i_op == &ubifs_file_inode_operations);
+
+	err = ubifs_init_security(dir, inode, &dentry->d_name);
+	if (err)
+		goto out_inode;
+
+	/* The dir size is updated by do_rename. */
+	insert_inode_hash(inode);
+
+	return inode;
+
+out_inode:
+	make_bad_inode(inode);
+	iput(inode);
+out_free:
+	fscrypt_free_filename(&nm);
+	ubifs_err(c, "cannot create whiteout file, error %d", err);
+	return ERR_PTR(err);
+}
+
+static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
+			 struct dentry *dentry, umode_t mode)
 {
 	struct inode *inode;
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
@@ -392,25 +440,13 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 	}
 	ui = ubifs_inode(inode);
 
-	if (whiteout) {
-		init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
-		ubifs_assert(c, inode->i_op == &ubifs_file_inode_operations);
-	}
-
 	err = ubifs_init_security(dir, inode, &dentry->d_name);
 	if (err)
 		goto out_inode;
 
 	mutex_lock(&ui->ui_mutex);
 	insert_inode_hash(inode);
-
-	if (whiteout) {
-		mark_inode_dirty(inode);
-		drop_nlink(inode);
-		*whiteout = inode;
-	} else {
-		d_tmpfile(dentry, inode);
-	}
+	d_tmpfile(dentry, inode);
 	ubifs_assert(c, ui->dirty);
 
 	instantiated = 1;
@@ -432,8 +468,6 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 	make_bad_inode(inode);
 	if (!instantiated)
 		iput(inode);
-	else if (whiteout)
-		iput(*whiteout);
 out_budg:
 	ubifs_release_budget(c, &req);
 	if (!instantiated)
@@ -443,12 +477,6 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry,
 	return err;
 }
 
-static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			 struct dentry *dentry, umode_t mode)
-{
-	return do_tmpfile(dir, dentry, mode, NULL);
-}
-
 /**
  * vfs_dent_type - get VFS directory entry type.
  * @type: UBIFS directory entry type
@@ -1266,17 +1294,19 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 					.dirtied_ino = 3 };
 	struct ubifs_budget_req ino_req = { .dirtied_ino = 1,
 			.dirtied_ino_d = ALIGN(old_inode_ui->data_len, 8) };
+	struct ubifs_budget_req wht_req;
 	struct timespec64 time;
 	unsigned int saved_nlink;
 	struct fscrypt_name old_nm, new_nm;
 
 	/*
-	 * Budget request settings: deletion direntry, new direntry, removing
-	 * the old inode, and changing old and new parent directory inodes.
+	 * Budget request settings:
+	 *   req: deletion direntry, new direntry, removing the old inode,
+	 *   and changing old and new parent directory inodes.
 	 *
-	 * However, this operation also marks the target inode as dirty and
-	 * does not write it, so we allocate budget for the target inode
-	 * separately.
+	 *   wht_req: new whiteout inode for RENAME_WHITEOUT.
+	 *
+	 *   ino_req: marks the target inode as dirty and does not write it.
 	 */
 
 	dbg_gen("dent '%pd' ino %lu in dir ino %lu to dent '%pd' in dir ino %lu flags 0x%x",
@@ -1326,7 +1356,6 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	if (flags & RENAME_WHITEOUT) {
 		union ubifs_dev_desc *dev = NULL;
-		struct ubifs_budget_req wht_req;
 
 		dev = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
 		if (!dev) {
@@ -1334,24 +1363,26 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 			goto out_release;
 		}
 
-		err = do_tmpfile(old_dir, old_dentry, S_IFCHR | WHITEOUT_MODE, &whiteout);
-		if (err) {
+		/*
+		 * The whiteout inode without dentry is pinned in memory,
+		 * umount won't happen during rename process because we
+		 * got parent dentry.
+		 */
+		whiteout = create_whiteout(old_dir, old_dentry);
+		if (IS_ERR(whiteout)) {
+			err = PTR_ERR(whiteout);
 			kfree(dev);
 			goto out_release;
 		}
 
-		spin_lock(&whiteout->i_lock);
-		whiteout->i_state |= I_LINKABLE;
-		spin_unlock(&whiteout->i_lock);
-
 		whiteout_ui = ubifs_inode(whiteout);
 		whiteout_ui->data = dev;
 		whiteout_ui->data_len = ubifs_encode_dev(dev, MKDEV(0, 0));
 		ubifs_assert(c, !whiteout_ui->dirty);
 
 		memset(&wht_req, 0, sizeof(struct ubifs_budget_req));
-		wht_req.dirtied_ino = 1;
-		wht_req.dirtied_ino_d = ALIGN(whiteout_ui->data_len, 8);
+		wht_req.new_ino = 1;
+		wht_req.new_ino_d = ALIGN(whiteout_ui->data_len, 8);
 		/*
 		 * To avoid deadlock between space budget (holds ui_mutex and
 		 * waits wb work) and writeback work(waits ui_mutex), do space
@@ -1359,6 +1390,11 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 		 */
 		err = ubifs_budget_space(c, &wht_req);
 		if (err) {
+			/*
+			 * Whiteout inode can not be written on flash by
+			 * ubifs_jnl_write_inode(), because it's neither
+			 * dirty nor zero-nlink.
+			 */
 			iput(whiteout);
 			goto out_release;
 		}
@@ -1433,17 +1469,11 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 		sync = IS_DIRSYNC(old_dir) || IS_DIRSYNC(new_dir);
 		if (unlink && IS_SYNC(new_inode))
 			sync = 1;
-	}
-
-	if (whiteout) {
-		inc_nlink(whiteout);
-		mark_inode_dirty(whiteout);
-
-		spin_lock(&whiteout->i_lock);
-		whiteout->i_state &= ~I_LINKABLE;
-		spin_unlock(&whiteout->i_lock);
-
-		iput(whiteout);
+		/*
+		 * S_SYNC flag of whiteout inherits from the old_dir, and we
+		 * have already checked the old dir inode. So there is no need
+		 * to check whiteout.
+		 */
 	}
 
 	err = ubifs_jnl_rename(c, old_dir, old_inode, &old_nm, new_dir,
@@ -1454,6 +1484,11 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 	unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
 	ubifs_release_budget(c, &req);
 
+	if (whiteout) {
+		ubifs_release_budget(c, &wht_req);
+		iput(whiteout);
+	}
+
 	mutex_lock(&old_inode_ui->ui_mutex);
 	release = old_inode_ui->dirty;
 	mark_inode_dirty_sync(old_inode);
@@ -1462,11 +1497,16 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 	if (release)
 		ubifs_release_budget(c, &ino_req);
 	if (IS_SYNC(old_inode))
-		err = old_inode->i_sb->s_op->write_inode(old_inode, NULL);
+		/*
+		 * Rename finished here. Although old inode cannot be updated
+		 * on flash, old ctime is not a big problem, don't return err
+		 * code to userspace.
+		 */
+		old_inode->i_sb->s_op->write_inode(old_inode, NULL);
 
 	fscrypt_free_filename(&old_nm);
 	fscrypt_free_filename(&new_nm);
-	return err;
+	return 0;
 
 out_cancel:
 	if (unlink) {
@@ -1487,11 +1527,11 @@ static int do_rename(struct inode *old_dir, struct dentry *old_dentry,
 				inc_nlink(old_dir);
 		}
 	}
+	unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
 	if (whiteout) {
-		drop_nlink(whiteout);
+		ubifs_release_budget(c, &wht_req);
 		iput(whiteout);
 	}
-	unlock_4_inodes(old_dir, new_dir, new_inode, whiteout);
 out_release:
 	ubifs_release_budget(c, &ino_req);
 	ubifs_release_budget(c, &req);
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 8ea680dba61e..75dab0ae3939 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1207,9 +1207,9 @@ int ubifs_jnl_xrename(struct ubifs_info *c, const struct inode *fst_dir,
  * @sync: non-zero if the write-buffer has to be synchronized
  *
  * This function implements the re-name operation which may involve writing up
- * to 4 inodes and 2 directory entries. It marks the written inodes as clean
- * and returns zero on success. In case of failure, a negative error code is
- * returned.
+ * to 4 inodes(new inode, whiteout inode, old and new parent directory inodes)
+ * and 2 directory entries. It marks the written inodes as clean and returns
+ * zero on success. In case of failure, a negative error code is returned.
  */
 int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		     const struct inode *old_inode,
@@ -1222,14 +1222,15 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	void *p;
 	union ubifs_key key;
 	struct ubifs_dent_node *dent, *dent2;
-	int err, dlen1, dlen2, ilen, lnum, offs, len, orphan_added = 0;
+	int err, dlen1, dlen2, ilen, wlen, lnum, offs, len, orphan_added = 0;
 	int aligned_dlen1, aligned_dlen2, plen = UBIFS_INO_NODE_SZ;
 	int last_reference = !!(new_inode && new_inode->i_nlink == 0);
 	int move = (old_dir != new_dir);
-	struct ubifs_inode *new_ui;
+	struct ubifs_inode *new_ui, *whiteout_ui;
 	u8 hash_old_dir[UBIFS_HASH_ARR_SZ];
 	u8 hash_new_dir[UBIFS_HASH_ARR_SZ];
 	u8 hash_new_inode[UBIFS_HASH_ARR_SZ];
+	u8 hash_whiteout_inode[UBIFS_HASH_ARR_SZ];
 	u8 hash_dent1[UBIFS_HASH_ARR_SZ];
 	u8 hash_dent2[UBIFS_HASH_ARR_SZ];
 
@@ -1249,9 +1250,20 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	} else
 		ilen = 0;
 
+	if (whiteout) {
+		whiteout_ui = ubifs_inode(whiteout);
+		ubifs_assert(c, mutex_is_locked(&whiteout_ui->ui_mutex));
+		ubifs_assert(c, whiteout->i_nlink == 1);
+		ubifs_assert(c, !whiteout_ui->dirty);
+		wlen = UBIFS_INO_NODE_SZ;
+		wlen += whiteout_ui->data_len;
+	} else
+		wlen = 0;
+
 	aligned_dlen1 = ALIGN(dlen1, 8);
 	aligned_dlen2 = ALIGN(dlen2, 8);
-	len = aligned_dlen1 + aligned_dlen2 + ALIGN(ilen, 8) + ALIGN(plen, 8);
+	len = aligned_dlen1 + aligned_dlen2 + ALIGN(ilen, 8) +
+	      ALIGN(wlen, 8) + ALIGN(plen, 8);
 	if (move)
 		len += plen;
 
@@ -1313,6 +1325,15 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		p += ALIGN(ilen, 8);
 	}
 
+	if (whiteout) {
+		pack_inode(c, p, whiteout, 0);
+		err = ubifs_node_calc_hash(c, p, hash_whiteout_inode);
+		if (err)
+			goto out_release;
+
+		p += ALIGN(wlen, 8);
+	}
+
 	if (!move) {
 		pack_inode(c, p, old_dir, 1);
 		err = ubifs_node_calc_hash(c, p, hash_old_dir);
@@ -1352,6 +1373,9 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		if (new_inode)
 			ubifs_wbuf_add_ino_nolock(&c->jheads[BASEHD].wbuf,
 						  new_inode->i_ino);
+		if (whiteout)
+			ubifs_wbuf_add_ino_nolock(&c->jheads[BASEHD].wbuf,
+						  whiteout->i_ino);
 	}
 	release_head(c, BASEHD);
 
@@ -1368,8 +1392,6 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		err = ubifs_tnc_add_nm(c, &key, lnum, offs, dlen2, hash_dent2, old_nm);
 		if (err)
 			goto out_ro;
-
-		ubifs_delete_orphan(c, whiteout->i_ino);
 	} else {
 		err = ubifs_add_dirt(c, lnum, dlen2);
 		if (err)
@@ -1390,6 +1412,15 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		offs += ALIGN(ilen, 8);
 	}
 
+	if (whiteout) {
+		ino_key_init(c, &key, whiteout->i_ino);
+		err = ubifs_tnc_add(c, &key, lnum, offs, wlen,
+				    hash_whiteout_inode);
+		if (err)
+			goto out_ro;
+		offs += ALIGN(wlen, 8);
+	}
+
 	ino_key_init(c, &key, old_dir->i_ino);
 	err = ubifs_tnc_add(c, &key, lnum, offs, plen, hash_old_dir);
 	if (err)
@@ -1410,6 +1441,11 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 		new_ui->synced_i_size = new_ui->ui_size;
 		spin_unlock(&new_ui->ui_lock);
 	}
+	/*
+	 * No need to mark whiteout inode clean.
+	 * Whiteout doesn't have non-zero size, no need to update
+	 * synced_i_size for whiteout_ui.
+	 */
 	mark_inode_clean(c, ubifs_inode(old_dir));
 	if (move)
 		mark_inode_clean(c, ubifs_inode(new_dir));
-- 
2.31.1

[PATCH v4 06/13] ubifs: Fix 'ui->dirty' race between do_tmpfile() and writeback work

[Zhihao Cheng]

'ui->dirty' is not protected by 'ui_mutex' in function do_tmpfile() which
may race with ubifs_write_inode[wb_workfn] to access/update 'ui->dirty',
finally dirty space is released twice.

	open(O_TMPFILE)                wb_workfn
do_tmpfile
  ubifs_budget_space(ino_req = { .dirtied_ino = 1})
  d_tmpfile // mark inode(tmpfile) dirty
  ubifs_jnl_update // without holding tmpfile's ui_mutex
    mark_inode_clean(ui)
      if (ui->dirty)
        ubifs_release_dirty_inode_budget(ui)  // release first time
                                   ubifs_write_inode
				     mutex_lock(&ui->ui_mutex)
                                     ubifs_release_dirty_inode_budget(ui)
				     // release second time
				     mutex_unlock(&ui->ui_mutex)
      ui->dirty = 0

Run generic/476 can reproduce following message easily
(See reproducer in [Link]):

  UBIFS error (ubi0:0 pid 2578): ubifs_assert_failed [ubifs]: UBIFS assert
  failed: c->bi.dd_growth >= 0, in fs/ubifs/budget.c:554
  UBIFS warning (ubi0:0 pid 2578): ubifs_ro_mode [ubifs]: switched to
  read-only mode, error -22
  Workqueue: writeback wb_workfn (flush-ubifs_0_0)
  Call Trace:
    ubifs_ro_mode+0x54/0x60 [ubifs]
    ubifs_assert_failed+0x4b/0x80 [ubifs]
    ubifs_release_budget+0x468/0x5a0 [ubifs]
    ubifs_release_dirty_inode_budget+0x53/0x80 [ubifs]
    ubifs_write_inode+0x121/0x1f0 [ubifs]
    ...
    wb_workfn+0x283/0x7b0

Fix it by holding tmpfile ubifs inode lock during ubifs_jnl_update().
Similar problem exists in whiteout renaming, but previous fix("ubifs:
Rename whiteout atomically") has solved the problem.

Fixes: 474b93704f32163 ("ubifs: Implement O_TMPFILE")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214765
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/dir.c | 60 +++++++++++++++++++++++++-------------------------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index deaf2d5dba5b..ebdc9aa04cbb 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -397,6 +397,32 @@ static struct inode *create_whiteout(struct inode *dir, struct dentry *dentry)
 	return ERR_PTR(err);
 }
 
+/**
+ * lock_2_inodes - a wrapper for locking two UBIFS inodes.
+ * @inode1: first inode
+ * @inode2: second inode
+ *
+ * We do not implement any tricks to guarantee strict lock ordering, because
+ * VFS has already done it for us on the @i_mutex. So this is just a simple
+ * wrapper function.
+ */
+static void lock_2_inodes(struct inode *inode1, struct inode *inode2)
+{
+	mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
+	mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
+}
+
+/**
+ * unlock_2_inodes - a wrapper for unlocking two UBIFS inodes.
+ * @inode1: first inode
+ * @inode2: second inode
+ */
+static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
+{
+	mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
+	mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
+}
+
 static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 			 struct dentry *dentry, umode_t mode)
 {
@@ -404,7 +430,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1};
 	struct ubifs_budget_req ino_req = { .dirtied_ino = 1 };
-	struct ubifs_inode *ui, *dir_ui = ubifs_inode(dir);
+	struct ubifs_inode *ui;
 	int err, instantiated = 0;
 	struct fscrypt_name nm;
 
@@ -452,18 +478,18 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	instantiated = 1;
 	mutex_unlock(&ui->ui_mutex);
 
-	mutex_lock(&dir_ui->ui_mutex);
+	lock_2_inodes(dir, inode);
 	err = ubifs_jnl_update(c, dir, &nm, inode, 1, 0);
 	if (err)
 		goto out_cancel;
-	mutex_unlock(&dir_ui->ui_mutex);
+	unlock_2_inodes(dir, inode);
 
 	ubifs_release_budget(c, &req);
 
 	return 0;
 
 out_cancel:
-	mutex_unlock(&dir_ui->ui_mutex);
+	unlock_2_inodes(dir, inode);
 out_inode:
 	make_bad_inode(inode);
 	if (!instantiated)
@@ -690,32 +716,6 @@ static int ubifs_dir_release(struct inode *dir, struct file *file)
 	return 0;
 }
 
-/**
- * lock_2_inodes - a wrapper for locking two UBIFS inodes.
- * @inode1: first inode
- * @inode2: second inode
- *
- * We do not implement any tricks to guarantee strict lock ordering, because
- * VFS has already done it for us on the @i_mutex. So this is just a simple
- * wrapper function.
- */
-static void lock_2_inodes(struct inode *inode1, struct inode *inode2)
-{
-	mutex_lock_nested(&ubifs_inode(inode1)->ui_mutex, WB_MUTEX_1);
-	mutex_lock_nested(&ubifs_inode(inode2)->ui_mutex, WB_MUTEX_2);
-}
-
-/**
- * unlock_2_inodes - a wrapper for unlocking two UBIFS inodes.
- * @inode1: first inode
- * @inode2: second inode
- */
-static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
-{
-	mutex_unlock(&ubifs_inode(inode2)->ui_mutex);
-	mutex_unlock(&ubifs_inode(inode1)->ui_mutex);
-}
-
 static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
 		      struct dentry *dentry)
 {
-- 
2.31.1

[PATCH v4 07/13] ubifs: Rectify space amount budget for mkdir/tmpfile operations

[Zhihao Cheng]

UBIFS should make sure the flash has enough space to store dirty (Data
that is newer than disk) data (in memory), space budget is exactly
designed to do that. If space budget calculates less data than we need,
'make_reservation()' will do more work(return -ENOSPC if no free space
lelf, sometimes we can see "cannot reserve xxx bytes in jhead xxx, error
-28" in ubifs error messages) with ubifs inodes locked, which may effect
other syscalls.

A simple way to decide how much space do we need when make a budget:
See how much space is needed by 'make_reservation()' in ubifs_jnl_xxx()
function according to corresponding operation.

It's better to report ENOSPC in ubifs_budget_space(), as early as we can.

Fixes: 474b93704f32163 ("ubifs: Implement O_TMPFILE")
Fixes: 1e51764a3c2ac05 ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/dir.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index ebdc9aa04cbb..7ae48f273feb 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -428,15 +428,18 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 {
 	struct inode *inode;
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
-	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1};
+	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
+					.dirtied_ino = 1};
 	struct ubifs_budget_req ino_req = { .dirtied_ino = 1 };
 	struct ubifs_inode *ui;
 	int err, instantiated = 0;
 	struct fscrypt_name nm;
 
 	/*
-	 * Budget request settings: new dirty inode, new direntry,
-	 * budget for dirtied inode will be released via writeback.
+	 * Budget request settings: new inode, new direntry, changing the
+	 * parent directory inode.
+	 * Allocate budget separately for new dirtied inode, the budget will
+	 * be released via writeback.
 	 */
 
 	dbg_gen("dent '%pd', mode %#hx in dir ino %lu",
@@ -979,7 +982,8 @@ static int ubifs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	struct ubifs_inode *dir_ui = ubifs_inode(dir);
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
 	int err, sz_change;
-	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1 };
+	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
+					.dirtied_ino = 1};
 	struct fscrypt_name nm;
 
 	/*
-- 
2.31.1

[PATCH v4 08/13] ubifs: setflags: Make dirtied_ino_d 8 bytes aligned

[Zhihao Cheng]

Make 'ui->data_len' aligned with 8 bytes before it is assigned to
dirtied_ino_d. Since 8871d84c8f8b0c6b("ubifs: convert to fileattr")
applied, 'setflags()' only affects regular files and directories, only
xattr inode, symlink inode and special inode(pipe/char_dev/block_dev)
have none- zero 'ui->data_len' field, so assertion
'!(req->dirtied_ino_d & 7)' cannot fail in ubifs_budget_space().
To avoid assertion fails in future evolution(eg. setflags can operate
special inodes), it's better to make dirtied_ino_d 8 bytes aligned,
after all aligned size is still zero for regular files.

Fixes: 1e51764a3c2ac05a ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ubifs/ioctl.c b/fs/ubifs/ioctl.c
index c6a863487780..71bcebe45f9c 100644
--- a/fs/ubifs/ioctl.c
+++ b/fs/ubifs/ioctl.c
@@ -108,7 +108,7 @@ static int setflags(struct inode *inode, int flags)
 	struct ubifs_inode *ui = ubifs_inode(inode);
 	struct ubifs_info *c = inode->i_sb->s_fs_info;
 	struct ubifs_budget_req req = { .dirtied_ino = 1,
-					.dirtied_ino_d = ui->data_len };
+			.dirtied_ino_d = ALIGN(ui->data_len, 8) };
 
 	err = ubifs_budget_space(c, &req);
 	if (err)
-- 
2.31.1

[PATCH v4 09/13] ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()

[Zhihao Cheng]

Function ubifs_wbuf_write_nolock() may access buf out of bounds in
following process:

ubifs_wbuf_write_nolock():
  aligned_len = ALIGN(len, 8);   // Assume len = 4089, aligned_len = 4096
  if (aligned_len <= wbuf->avail) ... // Not satisfy
  if (wbuf->used) {
    ubifs_leb_write()  // Fill some data in avail wbuf
    len -= wbuf->avail;   // len is still not 8-bytes aligned
    aligned_len -= wbuf->avail;
  }
  n = aligned_len >> c->max_write_shift;
  if (n) {
    n <<= c->max_write_shift;
    err = ubifs_leb_write(c, wbuf->lnum, buf + written,
                          wbuf->offs, n);
    // n > len, read out of bounds less than 8(n-len) bytes
  }

, which can be catched by KASAN:
  =========================================================
  BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0
  Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128
  Workqueue: writeback wb_workfn (flush-ubifs_0_0)
  Call Trace:
    kasan_report.cold+0x81/0x165
    nand_write_page_swecc+0xa9/0x160
    ubifs_leb_write+0xf2/0x1b0 [ubifs]
    ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs]
    write_head+0xdc/0x1c0 [ubifs]
    ubifs_jnl_write_inode+0x627/0x960 [ubifs]
    wb_workfn+0x8af/0xb80

Function ubifs_wbuf_write_nolock() accepts that parameter 'len' is not 8
bytes aligned, the 'len' represents the true length of buf (which is
allocated in 'ubifs_jnl_xxx', eg. ubifs_jnl_write_inode), so
ubifs_wbuf_write_nolock() must handle the length read from 'buf' carefully
to write leb safely.

Fetch a reproducer in [Link].

Fixes: 1e51764a3c2ac0 ("UBIFS: add new flash file system")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214785
Reported-by: Chengsong Ke <kechengsong@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/io.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 00b61dba62b7..b019dd6f7fa0 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -833,16 +833,42 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
 	 */
 	n = aligned_len >> c->max_write_shift;
 	if (n) {
-		n <<= c->max_write_shift;
+		int m = n - 1;
+
 		dbg_io("write %d bytes to LEB %d:%d", n, wbuf->lnum,
 		       wbuf->offs);
-		err = ubifs_leb_write(c, wbuf->lnum, buf + written,
-				      wbuf->offs, n);
+
+		if (m) {
+			/* '(n-1)<<c->max_write_shift < len' is always true. */
+			m <<= c->max_write_shift;
+			err = ubifs_leb_write(c, wbuf->lnum, buf + written,
+					      wbuf->offs, m);
+			if (err)
+				goto out;
+			wbuf->offs += m;
+			aligned_len -= m;
+			len -= m;
+			written += m;
+		}
+
+		/*
+		 * The non-written len of buf may be less than 'n' because
+		 * parameter 'len' is not 8 bytes aligned, so here we read
+		 * min(len, n) bytes from buf.
+		 */
+		n = 1 << c->max_write_shift;
+		memcpy(wbuf->buf, buf + written, min(len, n));
+		if (n > len) {
+			ubifs_assert(c, n - len < 8);
+			ubifs_pad(c, wbuf->buf + len, n - len);
+		}
+
+		err = ubifs_leb_write(c, wbuf->lnum, wbuf->buf, wbuf->offs, n);
 		if (err)
 			goto out;
 		wbuf->offs += n;
 		aligned_len -= n;
-		len -= n;
+		len -= min(len, n);
 		written += n;
 	}
 
-- 
2.31.1

[PATCH v4 10/13] ubifs: Fix to add refcount once page is set private

[Zhihao Cheng]

MM defined the rule [1] very clearly that once page was set with PG_private
flag, we should increment the refcount in that page, also main flows like
pageout(), migrate_page() will assume there is one additional page
reference count if page_has_private() returns true. Otherwise, we may
get a BUG in page migration:

  page:0000000080d05b9d refcount:-1 mapcount:0 mapping:000000005f4d82a8
  index:0xe2 pfn:0x14c12
  aops:ubifs_file_address_operations [ubifs] ino:8f1 dentry name:"f30e"
  flags: 0x1fffff80002405(locked|uptodate|owner_priv_1|private|node=0|
  zone=1|lastcpupid=0x1fffff)
  page dumped because: VM_BUG_ON_PAGE(page_count(page) != 0)
  ------------[ cut here ]------------
  kernel BUG at include/linux/page_ref.h:184!
  invalid opcode: 0000 [#1] SMP
  CPU: 3 PID: 38 Comm: kcompactd0 Not tainted 5.15.0-rc5
  RIP: 0010:migrate_page_move_mapping+0xac3/0xe70
  Call Trace:
    ubifs_migrate_page+0x22/0xc0 [ubifs]
    move_to_new_page+0xb4/0x600
    migrate_pages+0x1523/0x1cc0
    compact_zone+0x8c5/0x14b0
    kcompactd+0x2bc/0x560
    kthread+0x18c/0x1e0
    ret_from_fork+0x1f/0x30

Before the time, we should make clean a concept, what does refcount means
in page gotten from grab_cache_page_write_begin(). There are 2 situations:
Situation 1: refcount is 3, page is created by __page_cache_alloc.
  TYPE_A - the write process is using this page
  TYPE_B - page is assigned to one certain mapping by calling
	   __add_to_page_cache_locked()
  TYPE_C - page is added into pagevec list corresponding current cpu by
	   calling lru_cache_add()
Situation 2: refcount is 2, page is gotten from the mapping's tree
  TYPE_B - page has been assigned to one certain mapping
  TYPE_A - the write process is using this page (by calling
	   page_cache_get_speculative())
Filesystem releases one refcount by calling put_page() in xxx_write_end(),
the released refcount corresponds to TYPE_A (write task is using it). If
there are any processes using a page, page migration process will skip the
page by judging whether expected_page_refs() equals to page refcount.

The BUG is caused by following process:
    PA(cpu 0)                           kcompactd(cpu 1)
				compact_zone
ubifs_write_begin
  page_a = grab_cache_page_write_begin
    add_to_page_cache_lru
      lru_cache_add
        pagevec_add // put page into cpu 0's pagevec
  (refcnf = 3, for page creation process)
ubifs_write_end
  SetPagePrivate(page_a) // doesn't increase page count !
  unlock_page(page_a)
  put_page(page_a)  // refcnt = 2
				[...]

    PB(cpu 0)
filemap_read
  filemap_get_pages
    add_to_page_cache_lru
      lru_cache_add
        __pagevec_lru_add // traverse all pages in cpu 0's pagevec
	  __pagevec_lru_add_fn
	    SetPageLRU(page_a)
				isolate_migratepages
                                  isolate_migratepages_block
				    get_page_unless_zero(page_a)
				    // refcnt = 3
                                      list_add(page_a, from_list)
				migrate_pages(from_list)
				  __unmap_and_move
				    move_to_new_page
				      ubifs_migrate_page(page_a)
				        migrate_page_move_mapping
					  expected_page_refs get 3
                                  (migration[1] + mapping[1] + private[1])
	 release_pages
	   put_page_testzero(page_a) // refcnt = 3
                                          page_ref_freeze  // refcnt = 0
	     page_ref_dec_and_test(0 - 1 = -1)
                                          page_ref_unfreeze
                                            VM_BUG_ON_PAGE(-1 != 0, page)

UBIFS doesn't increase the page refcount after setting private flag, which
leads to page migration task believes the page is not used by any other
processes, so the page is migrated. This causes concurrent accessing on
page refcount between put_page() called by other process(eg. read process
calls lru_cache_add) and page_ref_unfreeze() called by migration task.

Actually zhangjun has tried to fix this problem [2] by recalculating page
refcnt in ubifs_migrate_page(). It's better to follow MM rules [1], because
just like Kirill suggested in [2], we need to check all users of
page_has_private() helper. Like f2fs does in [3], fix it by adding/deleting
refcount when setting/clearing private for a page. BTW, according to [4],
we set 'page->private' as 1 because ubifs just simply SetPagePrivate().
And, [5] provided a common helper to set/clear page private, ubifs can
use this helper following the example of iomap, afs, btrfs, etc.

Jump [6] to find a reproducer.

[1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com
[2] https://www.spinics.net/lists/linux-mtd/msg04018.html
[3] http://lkml.iu.edu/hypermail/linux/kernel/1903.0/03313.html
[4] https://lore.kernel.org/linux-f2fs-devel/20210422154705.GO3596236@casper.infradead.org
[5] https://lore.kernel.org/all/20200517214718.468-1-guoqing.jiang@cloud.ionos.com
[6] https://bugzilla.kernel.org/show_bug.cgi?id=214961

Fixes: 1e51764a3c2ac0 ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/file.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 5cfa28cd00cd..6b45a037a047 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -570,7 +570,7 @@ static int ubifs_write_end(struct file *file, struct address_space *mapping,
 	}
 
 	if (!PagePrivate(page)) {
-		SetPagePrivate(page);
+		attach_page_private(page, (void *)1);
 		atomic_long_inc(&c->dirty_pg_cnt);
 		__set_page_dirty_nobuffers(page);
 	}
@@ -947,7 +947,7 @@ static int do_writepage(struct page *page, int len)
 		release_existing_page_budget(c);
 
 	atomic_long_dec(&c->dirty_pg_cnt);
-	ClearPagePrivate(page);
+	detach_page_private(page);
 	ClearPageChecked(page);
 
 	kunmap(page);
@@ -1304,7 +1304,7 @@ static void ubifs_invalidatepage(struct page *page, unsigned int offset,
 		release_existing_page_budget(c);
 
 	atomic_long_dec(&c->dirty_pg_cnt);
-	ClearPagePrivate(page);
+	detach_page_private(page);
 	ClearPageChecked(page);
 }
 
@@ -1471,8 +1471,8 @@ static int ubifs_migrate_page(struct address_space *mapping,
 		return rc;
 
 	if (PagePrivate(page)) {
-		ClearPagePrivate(page);
-		SetPagePrivate(newpage);
+		detach_page_private(page);
+		attach_page_private(newpage, (void *)1);
 	}
 
 	if (mode != MIGRATE_SYNC_NO_COPY)
@@ -1496,7 +1496,7 @@ static int ubifs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 		return 0;
 	ubifs_assert(c, PagePrivate(page));
 	ubifs_assert(c, 0);
-	ClearPagePrivate(page);
+	detach_page_private(page);
 	ClearPageChecked(page);
 	return 1;
 }
@@ -1567,7 +1567,7 @@ static vm_fault_t ubifs_vm_page_mkwrite(struct vm_fault *vmf)
 	else {
 		if (!PageChecked(page))
 			ubifs_convert_page_budget(c);
-		SetPagePrivate(page);
+		attach_page_private(page, (void *)1);
 		atomic_long_inc(&c->dirty_pg_cnt);
 		__set_page_dirty_nobuffers(page);
 	}
-- 
2.31.1

[PATCH v4 11/13] ubi: fastmap: Return error code if memory allocation fails in add_aeb()

[Zhihao Cheng]

Abort fastmap scanning and return error code if memory allocation fails
in add_aeb(). Otherwise ubi will get wrong peb statistics information
after scanning.

Fixes: dbb7d2a88d2a7b ("UBI: Add fastmap core")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 drivers/mtd/ubi/fastmap.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 022af59906aa..6b5f1ffd961b 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -468,7 +468,9 @@ static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			if (err == UBI_IO_FF_BITFLIPS)
 				scrub = 1;
 
-			add_aeb(ai, free, pnum, ec, scrub);
+			ret = add_aeb(ai, free, pnum, ec, scrub);
+			if (ret)
+				goto out;
 			continue;
 		} else if (err == 0 || err == UBI_IO_BITFLIPS) {
 			dbg_bld("Found non empty PEB:%i in pool", pnum);
@@ -638,8 +640,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi,
 		if (fm_pos >= fm_size)
 			goto fail_bad;
 
-		add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum),
-			be32_to_cpu(fmec->ec), 0);
+		ret = add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 0);
+		if (ret)
+			goto fail;
 	}
 
 	/* read EC values from used list */
@@ -649,8 +653,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi,
 		if (fm_pos >= fm_size)
 			goto fail_bad;
 
-		add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
-			be32_to_cpu(fmec->ec), 0);
+		ret = add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 0);
+		if (ret)
+			goto fail;
 	}
 
 	/* read EC values from scrub list */
@@ -660,8 +666,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi,
 		if (fm_pos >= fm_size)
 			goto fail_bad;
 
-		add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
-			be32_to_cpu(fmec->ec), 1);
+		ret = add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 1);
+		if (ret)
+			goto fail;
 	}
 
 	/* read EC values from erase list */
@@ -671,8 +679,10 @@ static int ubi_attach_fastmap(struct ubi_device *ubi,
 		if (fm_pos >= fm_size)
 			goto fail_bad;
 
-		add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum),
-			be32_to_cpu(fmec->ec), 1);
+		ret = add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 1);
+		if (ret)
+			goto fail;
 	}
 
 	ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
-- 
2.31.1

[PATCH v4 12/13] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2

[Zhihao Cheng]

Fastmap pebs(pnum >= UBI_FM_MAX_START) won't be added into 'ai->fastmap'
while attaching ubi device if 'fm->used_blocks' is greater than 2, which
may cause warning from 'ubi_assert(ubi->good_peb_count == found_pebs)':

  UBI assert failed in ubi_wl_init at 1878 (pid 2409)
  Call Trace:
    ubi_wl_init.cold+0xae/0x2af [ubi]
    ubi_attach+0x1b0/0x780 [ubi]
    ubi_init+0x23a/0x3ad [ubi]
    load_module+0x22d2/0x2430

Reproduce:
  ID="0x20,0x33,0x00,0x00" # 16M 16KB PEB, 512 page
  modprobe nandsim id_bytes=$ID
  modprobe ubi mtd="0,0" fm_autoconvert  # Fastmap takes 2 pebs
  rmmod ubi
  modprobe ubi mtd="0,0" fm_autoconvert  # Attach by fastmap

Add all used fastmap pebs into list 'ai->fastmap' to make sure they can
be counted into 'found_pebs'.

Fixes: fdf10ed710c0aa ("ubi: Rework Fastmap attach base code")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 drivers/mtd/ubi/fastmap.c | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 6b5f1ffd961b..01dcdd94c9d2 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -828,24 +828,6 @@ static int find_fm_anchor(struct ubi_attach_info *ai)
 	return ret;
 }
 
-static struct ubi_ainf_peb *clone_aeb(struct ubi_attach_info *ai,
-				      struct ubi_ainf_peb *old)
-{
-	struct ubi_ainf_peb *new;
-
-	new = ubi_alloc_aeb(ai, old->pnum, old->ec);
-	if (!new)
-		return NULL;
-
-	new->vol_id = old->vol_id;
-	new->sqnum = old->sqnum;
-	new->lnum = old->lnum;
-	new->scrub = old->scrub;
-	new->copy_flag = old->copy_flag;
-
-	return new;
-}
-
 /**
  * ubi_scan_fastmap - scan the fastmap.
  * @ubi: UBI device object
@@ -865,7 +847,6 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 	struct ubi_vid_hdr *vh;
 	struct ubi_ec_hdr *ech;
 	struct ubi_fastmap_layout *fm;
-	struct ubi_ainf_peb *aeb;
 	int i, used_blocks, pnum, fm_anchor, ret = 0;
 	size_t fm_size;
 	__be32 crc, tmp_crc;
@@ -875,17 +856,6 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 	if (fm_anchor < 0)
 		return UBI_NO_FASTMAP;
 
-	/* Copy all (possible) fastmap blocks into our new attach structure. */
-	list_for_each_entry(aeb, &scan_ai->fastmap, u.list) {
-		struct ubi_ainf_peb *new;
-
-		new = clone_aeb(ai, aeb);
-		if (!new)
-			return -ENOMEM;
-
-		list_add(&new->u.list, &ai->fastmap);
-	}
-
 	down_write(&ubi->fm_protect);
 	memset(ubi->fm_buf, 0, ubi->fm_size);
 
@@ -1029,6 +999,11 @@ int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
 				"err: %i)", i, pnum, ret);
 			goto free_hdr;
 		}
+
+		/* Add all fastmap blocks into attach structure. */
+		ret = add_aeb(ai, &ai->fastmap, pnum, be64_to_cpu(ech->ec), 0);
+		if (ret)
+			goto free_hdr;
 	}
 
 	kfree(fmsb);
-- 
2.31.1

[PATCH v4 13/13] ubifs: ubifs_writepage: Mark page dirty after writing inode failed

[Zhihao Cheng]

There are two states for ubifs writing pages:
1. Dirty, Private
2. Not Dirty, Not Private

There is a third possibility which maybe related to [1] that page is
private but not dirty caused by following process:

          PA
lock(page)
ubifs_write_end
  attach_page_private		// set Private
    __set_page_dirty_nobuffers	// set Dirty
unlock(page)

write_cache_pages
  lock(page)
  clear_page_dirty_for_io(page)	// clear Dirty
  ubifs_writepage
    write_inode
    // fail, goto out, following codes are not executed
    // do_writepage
    //   set_page_writeback 	// set Writeback
    //   detach_page_private	// clear Private
    //   end_page_writeback 	// clear Writeback
    out:
    unlock(page)		// Private, Not Dirty

                                       PB
				ksys_fadvise64_64
				  generic_fadvise
				     invalidate_inode_page
				     // page is neither Dirty nor Writeback
				       invalidate_complete_page
				       // page_has_private is true
					 try_to_release_page
					   ubifs_releasepage
					     ubifs_assert(c, 0) !!!

Then we may get following assertion failed:
  UBIFS error (ubi0:0 pid 1492): ubifs_assert_failed [ubifs]:
  UBIFS assert failed: 0, in fs/ubifs/file.c:1499
  UBIFS warning (ubi0:0 pid 1492): ubifs_ro_mode [ubifs]:
  switched to read-only mode, error -22
  CPU: 2 PID: 1492 Comm: aa Not tainted 5.16.0-rc2-00012-g7bb767dee0ba-dirty
  Call Trace:
    dump_stack+0x13/0x1b
    ubifs_ro_mode+0x54/0x60 [ubifs]
    ubifs_assert_failed+0x4b/0x80 [ubifs]
    ubifs_releasepage+0x7e/0x1e0 [ubifs]
    try_to_release_page+0x57/0xe0
    invalidate_inode_page+0xfb/0x130
    invalidate_mapping_pagevec+0x12/0x20
    generic_fadvise+0x303/0x3c0
    vfs_fadvise+0x35/0x40
    ksys_fadvise64_64+0x4c/0xb0

Jump [2] to find a reproducer.

[1] https://linux-mtd.infradead.narkive.com/NQoBeT1u/patch-rfc-ubifs-fix-assert-failed-in-ubifs-set-page-dirty
[2] https://bugzilla.kernel.org/show_bug.cgi?id=215357

Fixes: 1e51764a3c2ac0 ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/ubifs/file.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 6b45a037a047..7cc2abcb70ae 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -1031,7 +1031,7 @@ static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
 		if (page->index >= synced_i_size >> PAGE_SHIFT) {
 			err = inode->i_sb->s_op->write_inode(inode, NULL);
 			if (err)
-				goto out_unlock;
+				goto out_redirty;
 			/*
 			 * The inode has been written, but the write-buffer has
 			 * not been synchronized, so in case of an unclean
@@ -1059,11 +1059,17 @@ static int ubifs_writepage(struct page *page, struct writeback_control *wbc)
 	if (i_size > synced_i_size) {
 		err = inode->i_sb->s_op->write_inode(inode, NULL);
 		if (err)
-			goto out_unlock;
+			goto out_redirty;
 	}
 
 	return do_writepage(page, len);
-
+out_redirty:
+	/*
+	 * redirty_page_for_writepage() won't call ubifs_dirty_inode() because
+	 * it passes I_DIRTY_PAGES flag while calling __mark_inode_dirty(), so
+	 * there is no need to do space budget for dirty inode.
+	 */
+	redirty_page_for_writepage(wbc, page);
 out_unlock:
 	unlock_page(page);
 	return err;
-- 
2.31.1