[PATCH 4.4 1/2] ext4: fix crashes in dioread_nolock mode

[PATCH 4.4 1/2] ext4: fix crashes in dioread_nolock mode

[Nathan Chancellor]

From: Jan Kara <jack@suse.cz>

commit 74dae4278546b897eb81784fdfcce872ddd8b2b8 upstream.

Competing overwrite DIO in dioread_nolock mode will just overwrite
pointer to io_end in the inode. This may result in data corruption or
extent conversion happening from IO completion interrupt because we
don't properly set buffer_defer_completion() when unlocked DIO races
with locked DIO to unwritten extent.

Since unlocked DIO doesn't need io_end for anything, just avoid
allocating it and corrupting pointer from inode for locked DIO.
A cleaner fix would be to avoid these games with io_end pointer from the
inode but that requires more intrusive changes so we leave that for
later.

Cc: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 fs/ext4/inode.c | 40 ++++++++++++++++++++--------------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f0cabc8c96cb..fa99cae9552b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3256,29 +3256,29 @@ static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 	 * case, we allocate an io_end structure to hook to the iocb.
 	 */
 	iocb->private = NULL;
-	ext4_inode_aio_set(inode, NULL);
-	if (!is_sync_kiocb(iocb)) {
-		io_end = ext4_init_io_end(inode, GFP_NOFS);
-		if (!io_end) {
-			ret = -ENOMEM;
-			goto retake_lock;
-		}
-		/*
-		 * Grab reference for DIO. Will be dropped in ext4_end_io_dio()
-		 */
-		iocb->private = ext4_get_io_end(io_end);
-		/*
-		 * we save the io structure for current async direct
-		 * IO, so that later ext4_map_blocks() could flag the
-		 * io structure whether there is a unwritten extents
-		 * needs to be converted when IO is completed.
-		 */
-		ext4_inode_aio_set(inode, io_end);
-	}
-
 	if (overwrite) {
 		get_block_func = ext4_get_block_write_nolock;
 	} else {
+		ext4_inode_aio_set(inode, NULL);
+		if (!is_sync_kiocb(iocb)) {
+			io_end = ext4_init_io_end(inode, GFP_NOFS);
+			if (!io_end) {
+				ret = -ENOMEM;
+				goto retake_lock;
+			}
+			/*
+			 * Grab reference for DIO. Will be dropped in
+			 * ext4_end_io_dio()
+			 */
+			iocb->private = ext4_get_io_end(io_end);
+			/*
+			 * we save the io structure for current async direct
+			 * IO, so that later ext4_map_blocks() could flag the
+			 * io structure whether there is a unwritten extents
+			 * needs to be converted when IO is completed.
+			 */
+			ext4_inode_aio_set(inode, io_end);
+		}
 		get_block_func = ext4_get_block_write;
 		dio_flags = DIO_LOCKING;
 	}
-- 
2.17.0

[PATCH 4.4 2/2] ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()

[Nathan Chancellor]

From: Theodore Ts'o <tytso@mit.edu>

commit c755e251357a0cee0679081f08c3f4ba797a8009 upstream.

The xattr_sem deadlock problems fixed in commit 2e81a4eeedca: "ext4:
avoid deadlock when expanding inode size" didn't include the use of
xattr_sem in fs/ext4/inline.c.  With the addition of project quota
which added a new extra inode field, this exposed deadlocks in the
inline_data code similar to the ones fixed by 2e81a4eeedca.

The deadlock can be reproduced via:

   dmesg -n 7
   mke2fs -t ext4 -O inline_data -Fq -I 256 /dev/vdc 32768
   mount -t ext4 -o debug_want_extra_isize=24 /dev/vdc /vdc
   mkdir /vdc/a
   umount /vdc
   mount -t ext4 /dev/vdc /vdc
   echo foo > /vdc/a/foo

and looks like this:

[   11.158815]
[   11.160276] =============================================
[   11.161960] [ INFO: possible recursive locking detected ]
[   11.161960] 4.10.0-rc3-00015-g011b30a8a3cf #160 Tainted: G        W
[   11.161960] ---------------------------------------------
[   11.161960] bash/2519 is trying to acquire lock:
[   11.161960]  (&ei->xattr_sem){++++..}, at: [<c1225a4b>] ext4_expand_extra_isize_ea+0x3d/0x4cd
[   11.161960]
[   11.161960] but task is already holding lock:
[   11.161960]  (&ei->xattr_sem){++++..}, at: [<c1227941>] ext4_try_add_inline_entry+0x3a/0x152
[   11.161960]
[   11.161960] other info that might help us debug this:
[   11.161960]  Possible unsafe locking scenario:
[   11.161960]
[   11.161960]        CPU0
[   11.161960]        ----
[   11.161960]   lock(&ei->xattr_sem);
[   11.161960]   lock(&ei->xattr_sem);
[   11.161960]
[   11.161960]  *** DEADLOCK ***
[   11.161960]
[   11.161960]  May be due to missing lock nesting notation
[   11.161960]
[   11.161960] 4 locks held by bash/2519:
[   11.161960]  #0:  (sb_writers#3){.+.+.+}, at: [<c11a2414>] mnt_want_write+0x1e/0x3e
[   11.161960]  #1:  (&type->i_mutex_dir_key){++++++}, at: [<c119508b>] path_openat+0x338/0x67a
[   11.161960]  #2:  (jbd2_handle){++++..}, at: [<c123314a>] start_this_handle+0x582/0x622
[   11.161960]  #3:  (&ei->xattr_sem){++++..}, at: [<c1227941>] ext4_try_add_inline_entry+0x3a/0x152
[   11.161960]
[   11.161960] stack backtrace:
[   11.161960] CPU: 0 PID: 2519 Comm: bash Tainted: G        W       4.10.0-rc3-00015-g011b30a8a3cf #160
[   11.161960] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.1-1 04/01/2014
[   11.161960] Call Trace:
[   11.161960]  dump_stack+0x72/0xa3
[   11.161960]  __lock_acquire+0xb7c/0xcb9
[   11.161960]  ? kvm_clock_read+0x1f/0x29
[   11.161960]  ? __lock_is_held+0x36/0x66
[   11.161960]  ? __lock_is_held+0x36/0x66
[   11.161960]  lock_acquire+0x106/0x18a
[   11.161960]  ? ext4_expand_extra_isize_ea+0x3d/0x4cd
[   11.161960]  down_write+0x39/0x72
[   11.161960]  ? ext4_expand_extra_isize_ea+0x3d/0x4cd
[   11.161960]  ext4_expand_extra_isize_ea+0x3d/0x4cd
[   11.161960]  ? _raw_read_unlock+0x22/0x2c
[   11.161960]  ? jbd2_journal_extend+0x1e2/0x262
[   11.161960]  ? __ext4_journal_get_write_access+0x3d/0x60
[   11.161960]  ext4_mark_inode_dirty+0x17d/0x26d
[   11.161960]  ? ext4_add_dirent_to_inline.isra.12+0xa5/0xb2
[   11.161960]  ext4_add_dirent_to_inline.isra.12+0xa5/0xb2
[   11.161960]  ext4_try_add_inline_entry+0x69/0x152
[   11.161960]  ext4_add_entry+0xa3/0x848
[   11.161960]  ? __brelse+0x14/0x2f
[   11.161960]  ? _raw_spin_unlock_irqrestore+0x44/0x4f
[   11.161960]  ext4_add_nondir+0x17/0x5b
[   11.161960]  ext4_create+0xcf/0x133
[   11.161960]  ? ext4_mknod+0x12f/0x12f
[   11.161960]  lookup_open+0x39e/0x3fb
[   11.161960]  ? __wake_up+0x1a/0x40
[   11.161960]  ? lock_acquire+0x11e/0x18a
[   11.161960]  path_openat+0x35c/0x67a
[   11.161960]  ? sched_clock_cpu+0xd7/0xf2
[   11.161960]  do_filp_open+0x36/0x7c
[   11.161960]  ? _raw_spin_unlock+0x22/0x2c
[   11.161960]  ? __alloc_fd+0x169/0x173
[   11.161960]  do_sys_open+0x59/0xcc
[   11.161960]  SyS_open+0x1d/0x1f
[   11.161960]  do_int80_syscall_32+0x4f/0x61
[   11.161960]  entry_INT80_32+0x2f/0x2f
[   11.161960] EIP: 0xb76ad469
[   11.161960] EFLAGS: 00000286 CPU: 0
[   11.161960] EAX: ffffffda EBX: 08168ac8 ECX: 00008241 EDX: 000001b6
[   11.161960] ESI: b75e46bc EDI: b7755000 EBP: bfbdb108 ESP: bfbdafc0
[   11.161960]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b

Cc: stable@vger.kernel.org # 3.10 (requires 2e81a4eeedca as a prereq)
Reported-by: George Spelvin <linux@sciencehorizons.net>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 fs/ext4/inline.c | 66 ++++++++++++++++++++++--------------------------
 fs/ext4/xattr.c  | 30 +++++++++-------------
 fs/ext4/xattr.h  | 32 +++++++++++++++++++++++
 3 files changed, 74 insertions(+), 54 deletions(-)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index dad8e7bdf0a6..3006b81c107f 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -376,7 +376,7 @@ out:
 static int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
 				    unsigned int len)
 {
-	int ret, size;
+	int ret, size, no_expand;
 	struct ext4_inode_info *ei = EXT4_I(inode);
 
 	if (!ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))
@@ -386,15 +386,14 @@ static int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
 	if (size < len)
 		return -ENOSPC;
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 
 	if (ei->i_inline_off)
 		ret = ext4_update_inline_data(handle, inode, len);
 	else
 		ret = ext4_create_inline_data(handle, inode, len);
 
-	up_write(&EXT4_I(inode)->xattr_sem);
-
+	ext4_write_unlock_xattr(inode, &no_expand);
 	return ret;
 }
 
@@ -523,7 +522,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,
 					      struct inode *inode,
 					      unsigned flags)
 {
-	int ret, needed_blocks;
+	int ret, needed_blocks, no_expand;
 	handle_t *handle = NULL;
 	int retries = 0, sem_held = 0;
 	struct page *page = NULL;
@@ -563,7 +562,7 @@ retry:
 		goto out;
 	}
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 	sem_held = 1;
 	/* If some one has already done this for us, just exit. */
 	if (!ext4_has_inline_data(inode)) {
@@ -599,7 +598,7 @@ retry:
 		page_cache_release(page);
 		page = NULL;
 		ext4_orphan_add(handle, inode);
-		up_write(&EXT4_I(inode)->xattr_sem);
+		ext4_write_unlock_xattr(inode, &no_expand);
 		sem_held = 0;
 		ext4_journal_stop(handle);
 		handle = NULL;
@@ -625,7 +624,7 @@ out:
 		page_cache_release(page);
 	}
 	if (sem_held)
-		up_write(&EXT4_I(inode)->xattr_sem);
+		ext4_write_unlock_xattr(inode, &no_expand);
 	if (handle)
 		ext4_journal_stop(handle);
 	brelse(iloc.bh);
@@ -718,7 +717,7 @@ convert:
 int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 			       unsigned copied, struct page *page)
 {
-	int ret;
+	int ret, no_expand;
 	void *kaddr;
 	struct ext4_iloc iloc;
 
@@ -736,7 +735,7 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 		goto out;
 	}
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 	BUG_ON(!ext4_has_inline_data(inode));
 
 	kaddr = kmap_atomic(page);
@@ -746,7 +745,7 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len,
 	/* clear page dirty so that writepages wouldn't work for us. */
 	ClearPageDirty(page);
 
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 	brelse(iloc.bh);
 out:
 	return copied;
@@ -757,7 +756,7 @@ ext4_journalled_write_inline_data(struct inode *inode,
 				  unsigned len,
 				  struct page *page)
 {
-	int ret;
+	int ret, no_expand;
 	void *kaddr;
 	struct ext4_iloc iloc;
 
@@ -767,11 +766,11 @@ ext4_journalled_write_inline_data(struct inode *inode,
 		return NULL;
 	}
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 	kaddr = kmap_atomic(page);
 	ext4_write_inline_data(inode, &iloc, kaddr, 0, len);
 	kunmap_atomic(kaddr);
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 
 	return iloc.bh;
 }
@@ -1255,7 +1254,7 @@ out:
 int ext4_try_add_inline_entry(handle_t *handle, struct ext4_filename *fname,
 			      struct dentry *dentry, struct inode *inode)
 {
-	int ret, inline_size;
+	int ret, inline_size, no_expand;
 	void *inline_start;
 	struct ext4_iloc iloc;
 	struct inode *dir = d_inode(dentry->d_parent);
@@ -1264,7 +1263,7 @@ int ext4_try_add_inline_entry(handle_t *handle, struct ext4_filename *fname,
 	if (ret)
 		return ret;
 
-	down_write(&EXT4_I(dir)->xattr_sem);
+	ext4_write_lock_xattr(dir, &no_expand);
 	if (!ext4_has_inline_data(dir))
 		goto out;
 
@@ -1310,7 +1309,7 @@ int ext4_try_add_inline_entry(handle_t *handle, struct ext4_filename *fname,
 
 out:
 	ext4_mark_inode_dirty(handle, dir);
-	up_write(&EXT4_I(dir)->xattr_sem);
+	ext4_write_unlock_xattr(dir, &no_expand);
 	brelse(iloc.bh);
 	return ret;
 }
@@ -1670,7 +1669,7 @@ int ext4_delete_inline_entry(handle_t *handle,
 			     struct buffer_head *bh,
 			     int *has_inline_data)
 {
-	int err, inline_size;
+	int err, inline_size, no_expand;
 	struct ext4_iloc iloc;
 	void *inline_start;
 
@@ -1678,7 +1677,7 @@ int ext4_delete_inline_entry(handle_t *handle,
 	if (err)
 		return err;
 
-	down_write(&EXT4_I(dir)->xattr_sem);
+	ext4_write_lock_xattr(dir, &no_expand);
 	if (!ext4_has_inline_data(dir)) {
 		*has_inline_data = 0;
 		goto out;
@@ -1713,7 +1712,7 @@ int ext4_delete_inline_entry(handle_t *handle,
 
 	ext4_show_inline_dir(dir, iloc.bh, inline_start, inline_size);
 out:
-	up_write(&EXT4_I(dir)->xattr_sem);
+	ext4_write_unlock_xattr(dir, &no_expand);
 	brelse(iloc.bh);
 	if (err != -ENOENT)
 		ext4_std_error(dir->i_sb, err);
@@ -1812,11 +1811,11 @@ out:
 
 int ext4_destroy_inline_data(handle_t *handle, struct inode *inode)
 {
-	int ret;
+	int ret, no_expand;
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 	ret = ext4_destroy_inline_data_nolock(handle, inode);
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 
 	return ret;
 }
@@ -1901,7 +1900,7 @@ out:
 void ext4_inline_data_truncate(struct inode *inode, int *has_inline)
 {
 	handle_t *handle;
-	int inline_size, value_len, needed_blocks;
+	int inline_size, value_len, needed_blocks, no_expand;
 	size_t i_size;
 	void *value = NULL;
 	struct ext4_xattr_ibody_find is = {
@@ -1918,7 +1917,7 @@ void ext4_inline_data_truncate(struct inode *inode, int *has_inline)
 	if (IS_ERR(handle))
 		return;
 
-	down_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_lock_xattr(inode, &no_expand);
 	if (!ext4_has_inline_data(inode)) {
 		*has_inline = 0;
 		ext4_journal_stop(handle);
@@ -1976,7 +1975,7 @@ out_error:
 	up_write(&EXT4_I(inode)->i_data_sem);
 out:
 	brelse(is.iloc.bh);
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 	kfree(value);
 	if (inode->i_nlink)
 		ext4_orphan_del(handle, inode);
@@ -1992,7 +1991,7 @@ out:
 
 int ext4_convert_inline_data(struct inode *inode)
 {
-	int error, needed_blocks;
+	int error, needed_blocks, no_expand;
 	handle_t *handle;
 	struct ext4_iloc iloc;
 
@@ -2014,15 +2013,10 @@ int ext4_convert_inline_data(struct inode *inode)
 		goto out_free;
 	}
 
-	down_write(&EXT4_I(inode)->xattr_sem);
-	if (!ext4_has_inline_data(inode)) {
-		up_write(&EXT4_I(inode)->xattr_sem);
-		goto out;
-	}
-
-	error = ext4_convert_inline_data_nolock(handle, inode, &iloc);
-	up_write(&EXT4_I(inode)->xattr_sem);
-out:
+	ext4_write_lock_xattr(inode, &no_expand);
+	if (ext4_has_inline_data(inode))
+		error = ext4_convert_inline_data_nolock(handle, inode, &iloc);
+	ext4_write_unlock_xattr(inode, &no_expand);
 	ext4_journal_stop(handle);
 out_free:
 	brelse(iloc.bh);
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 8d661b3c47b6..c7cad05aed27 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1117,16 +1117,14 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 	struct ext4_xattr_block_find bs = {
 		.s = { .not_found = -ENODATA, },
 	};
-	unsigned long no_expand;
+	int no_expand;
 	int error;
 
 	if (!name)
 		return -EINVAL;
 	if (strlen(name) > 255)
 		return -ERANGE;
-	down_write(&EXT4_I(inode)->xattr_sem);
-	no_expand = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
-	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
+	ext4_write_lock_xattr(inode, &no_expand);
 
 	error = ext4_reserve_inode_write(handle, inode, &is.iloc);
 	if (error)
@@ -1187,7 +1185,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 		ext4_xattr_update_super_block(handle, inode->i_sb);
 		inode->i_ctime = ext4_current_time(inode);
 		if (!value)
-			ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
+			no_expand = 0;
 		error = ext4_mark_iloc_dirty(handle, inode, &is.iloc);
 		/*
 		 * The bh is consumed by ext4_mark_iloc_dirty, even with
@@ -1201,9 +1199,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
 cleanup:
 	brelse(is.iloc.bh);
 	brelse(bs.bh);
-	if (no_expand == 0)
-		ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 	return error;
 }
 
@@ -1287,12 +1283,11 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 	int error = 0, tried_min_extra_isize = 0;
 	int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
 	int isize_diff;	/* How much do we need to grow i_extra_isize */
+	int no_expand;
+
+	if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
+		return 0;
 
-	down_write(&EXT4_I(inode)->xattr_sem);
-	/*
-	 * Set EXT4_STATE_NO_EXPAND to avoid recursion when marking inode dirty
-	 */
-	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 retry:
 	isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
 	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
@@ -1486,8 +1481,7 @@ retry:
 	}
 	brelse(bh);
 out:
-	ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
-	up_write(&EXT4_I(inode)->xattr_sem);
+	ext4_write_unlock_xattr(inode, &no_expand);
 	return 0;
 
 cleanup:
@@ -1499,10 +1493,10 @@ cleanup:
 	kfree(bs);
 	brelse(bh);
 	/*
-	 * We deliberately leave EXT4_STATE_NO_EXPAND set here since inode
-	 * size expansion failed.
+	 * Inode size expansion failed; don't try again
 	 */
-	up_write(&EXT4_I(inode)->xattr_sem);
+	no_expand = 1;
+	ext4_write_unlock_xattr(inode, &no_expand);
 	return error;
 }
 
diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
index ddc0957760ba..c000ed398555 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -101,6 +101,38 @@ extern const struct xattr_handler ext4_xattr_security_handler;
 
 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
 
+/*
+ * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
+ * The first is to signal that there the inline xattrs and data are
+ * taking up so much space that we might as well not keep trying to
+ * expand it.  The second is that xattr_sem is taken for writing, so
+ * we shouldn't try to recurse into the inode expansion.  For this
+ * second case, we need to make sure that we take save and restore the
+ * NO_EXPAND state flag appropriately.
+ */
+static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
+{
+	down_write(&EXT4_I(inode)->xattr_sem);
+	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
+	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
+}
+
+static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
+{
+	if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
+		return 0;
+	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
+	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
+	return 1;
+}
+
+static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
+{
+	if (*save == 0)
+		ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
+	up_write(&EXT4_I(inode)->xattr_sem);
+}
+
 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
 
 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
-- 
2.17.0

Re: [PATCH 4.4 1/2] ext4: fix crashes in dioread_nolock mode

[Greg Kroah-Hartman]

On Sun, Apr 22, 2018 at 01:11:31AM -0700, Nathan Chancellor wrote:
> From: Jan Kara <jack@suse.cz>
> 
> commit 74dae4278546b897eb81784fdfcce872ddd8b2b8 upstream.
> 
> Competing overwrite DIO in dioread_nolock mode will just overwrite
> pointer to io_end in the inode. This may result in data corruption or
> extent conversion happening from IO completion interrupt because we
> don't properly set buffer_defer_completion() when unlocked DIO races
> with locked DIO to unwritten extent.
> 
> Since unlocked DIO doesn't need io_end for anything, just avoid
> allocating it and corrupting pointer from inode for locked DIO.
> A cleaner fix would be to avoid these games with io_end pointer from the
> inode but that requires more intrusive changes so we leave that for
> later.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>  fs/ext4/inode.c | 40 ++++++++++++++++++++--------------------
>  1 file changed, 20 insertions(+), 20 deletions(-)
> 

Both patches now queued up, thanks!

greg k-h