fs: ext4: initialize fsdata in pagecache_write()

stable inclusion
from stable-v5.10.163
commit 769469f8f188573431927be905aff50712b34c5a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7PJ9N

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=769469f8f188573431927be905aff50712b34c5a



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[ Upstream commit 956510c0 ]

When aops->write_begin() does not initialize fsdata, KMSAN reports
an error passing the latter to aops->write_end().

Fix this by unconditionally initializing fsdata.

Cc: Eric Biggers <ebiggers@kernel.org>
Fixes: c93d8f88 ("ext4: add basic fs-verity support")
Reported-by:  <syzbot+9767be679ef5016b6082@syzkaller.appspotmail.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20221121112134.407362-1-glider@google.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: zhaoxiaoqiang11 <zhaoxiaoqiang11@jd.com>