From: Amir Goldstein <amir73il@gmail.com> mainline inclusion from mainline-v6.8-rc1 commit 2f4d8ad82511a336f8a805e3759c5189a25bb286 category: feature bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBHLU4 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In vfs code, file_start_write() is usually called after the permission hook in rw_verify_area(). btrfs_ioctl_encoded_write() in an exception to this rule. Move file_start_write() to after the rw_verify_area() check in encoded write to make the permission hook "start-write-safe". This is needed for fanotify "pre content" events. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Link: https://lore.kernel.org/r/20231122122715.2561213-9-amir73il@gmail.com Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- fs/btrfs/ioctl.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index d61bd816808c..3d1cb018f3c4 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -4559,29 +4559,29 @@ static int btrfs_ioctl_encoded_write(struct file *file, void __user *argp, bool if (ret < 0) goto out_acct; - file_start_write(file); - if (iov_iter_count(&iter) == 0) { ret = 0; - goto out_end_write; + goto out_iov; } pos = args.offset; ret = rw_verify_area(WRITE, file, &pos, args.len); if (ret < 0) - goto out_end_write; + goto out_iov; init_sync_kiocb(&kiocb, file); ret = kiocb_set_rw_flags(&kiocb, 0); if (ret) - goto out_end_write; + goto out_iov; kiocb.ki_pos = pos; + file_start_write(file); + ret = btrfs_do_write_iter(&kiocb, &iter, &args); if (ret > 0) fsnotify_modify(file); -out_end_write: file_end_write(file); +out_iov: kfree(iov); out_acct: if (ret > 0) -- 2.39.2