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From:   Park Ju Hyung <qkrwngud825@gmail.com>
To:     linux-fsdevel@vger.kernel.org
Cc:     Park Ju Hyung <qkrwngud825@gmail.com>,
        Namjae Jeon <namjae.jeon@samsung.com>,
        Sungjong Seo <sj1557.seo@samsung.com>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] exfat: implement "quiet" option for setattr
Date:   Sat, 27 Jun 2020 21:55:09 +0900
Message-Id: <20200627125509.142393-1-qkrwngud825@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Few programs, especially old ones, simply don't want to work
if there isn't a POSIX-compliant setattr.

Follow vfat and implement a new "quiet" option to workaround this.

Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
---
 fs/exfat/exfat_fs.h |  2 ++
 fs/exfat/file.c     | 13 +++++++++++--
 fs/exfat/super.c    |  7 +++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 3aed8e22087a..66837baf42d2 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -201,6 +201,8 @@ struct exfat_mount_options {
 	unsigned short allow_utime;
 	/* charset for filename input/display */
 	char *iocharset;
+	/* fake return success on setattr(e.g. chmods/chowns) */
+	unsigned char quiet;
 	/* on error: continue, panic, remount-ro */
 	enum exfat_error_mode errors;
 	unsigned utf8:1, /* Use of UTF-8 character set */
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 6707f3eb09b5..2ed6be7cab15 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -295,7 +295,7 @@ int exfat_setattr(struct dentry *dentry, struct iattr *attr)
 	    attr->ia_size > i_size_read(inode)) {
 		error = exfat_cont_expand(inode, attr->ia_size);
 		if (error || attr->ia_valid == ATTR_SIZE)
-			return error;
+			goto out;
 		attr->ia_valid &= ~ATTR_SIZE;
 	}
 
@@ -309,8 +309,11 @@ int exfat_setattr(struct dentry *dentry, struct iattr *attr)
 
 	error = setattr_prepare(dentry, attr);
 	attr->ia_valid = ia_valid;
-	if (error)
+	if (error) {
+		if (sbi->options.quiet)
+			error = 0;
 		goto out;
+	}
 
 	if (((attr->ia_valid & ATTR_UID) &&
 	     !uid_eq(attr->ia_uid, sbi->options.fs_uid)) ||
@@ -322,6 +325,12 @@ int exfat_setattr(struct dentry *dentry, struct iattr *attr)
 		goto out;
 	}
 
+	if (error) {
+		if (sbi->options.quiet)
+			error = 0;
+		goto out;
+	}
+
 	/*
 	 * We don't return -EPERM here. Yes, strange, but this is too
 	 * old behavior.
diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index b5bf6dedbe11..030db33eed35 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -145,6 +145,8 @@ static int exfat_show_options(struct seq_file *m, struct dentry *root)
 	seq_printf(m, ",fmask=%04o,dmask=%04o", opts->fs_fmask, opts->fs_dmask);
 	if (opts->allow_utime)
 		seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
+	if (opts->quiet)
+		seq_puts(m, ",quiet");
 	if (opts->utf8)
 		seq_puts(m, ",iocharset=utf8");
 	else if (sbi->nls_io)
@@ -198,6 +200,7 @@ enum {
 	Opt_fmask,
 	Opt_allow_utime,
 	Opt_charset,
+	Opt_quiet,
 	Opt_errors,
 	Opt_discard,
 	Opt_time_offset,
@@ -224,6 +227,7 @@ static const struct fs_parameter_spec exfat_parameters[] = {
 	fsparam_u32oct("fmask",			Opt_fmask),
 	fsparam_u32oct("allow_utime",		Opt_allow_utime),
 	fsparam_string("iocharset",		Opt_charset),
+	fsparam_flag("quiet",			Opt_quiet),
 	fsparam_enum("errors",			Opt_errors, exfat_param_enums),
 	fsparam_flag("discard",			Opt_discard),
 	fsparam_s32("time_offset",		Opt_time_offset),
@@ -274,6 +278,9 @@ static int exfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		opts->iocharset = param->string;
 		param->string = NULL;
 		break;
+	case Opt_quiet:
+		opts->quiet = 1;
+		break;
 	case Opt_errors:
 		opts->errors = result.uint_32;
 		break;
-- 
2.27.0