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From: Zev Weiss <zev@bewilderbeest.net>
To: openbmc@lists.ozlabs.org
Cc: devicetree@vger.kernel.org, "Zev Weiss" <zev@bewilderbeest.net>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	linux-kernel@vger.kernel.org, "Rob Herring" <robh+dt@kernel.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Jeremy Kerr" <jk@codeconstruct.com.au>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>
Subject: [PATCH 2/9] sysfs: add growable flag to struct bin_attribute
Date: Wed,  6 Oct 2021 17:09:47 -0700	[thread overview]
Message-ID: <20211007000954.30621-3-zev@bewilderbeest.net> (raw)
In-Reply-To: <20211007000954.30621-1-zev@bewilderbeest.net>

Previously, sysfs_kf_bin_write() unconditionally disallowed writing
past the existing size of the file.  In order to support mutable
device-tree status properties (which are bin_attributes), we need to
be able to write a longer value over a shorter existing one
(e.g. writing "reserved\n" over "okay\0").  bin_attributes that
require this can now set the growable flag to disable that checking
and allow arbitrary amounts of data to be written at arbitrary
offsets.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
---
 fs/sysfs/file.c       | 2 +-
 include/linux/sysfs.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index b2b85be95adf..156df003ea8f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -147,7 +147,7 @@ static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
 	struct kobject *kobj = of->kn->parent->priv;
 	loff_t size = file_inode(of->file)->i_size;
 
-	if (size) {
+	if (!battr->growable && size) {
 		if (size <= pos)
 			return -EFBIG;
 		count = min_t(ssize_t, count, size - pos);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 49de5189cf88..f8a56094c6c9 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -175,6 +175,7 @@ struct address_space;
 struct bin_attribute {
 	struct attribute	attr;
 	size_t			size;
+	bool			growable:1;
 	void			*private;
 	struct address_space *(*f_mapping)(void);
 	ssize_t (*read)(struct file *, struct kobject *, struct bin_attribute *,
-- 
2.33.0


  parent reply	other threads:[~2021-10-07  0:11 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-07  0:09 [PATCH 0/9] Dynamic DT device nodes Zev Weiss
2021-10-07  0:09 ` [PATCH 1/9] sysfs: add sysfs_remove_bin_file_self() function Zev Weiss
2021-10-07  5:23   ` Greg Kroah-Hartman
2021-10-07  5:58     ` Zev Weiss
2021-10-07  6:12       ` Greg Kroah-Hartman
2021-10-07  6:55         ` Zev Weiss
2021-10-07  0:09 ` Zev Weiss [this message]
2021-10-07  0:09 ` [PATCH 3/9] lib/string: add sysfs_buf_streq() Zev Weiss
2021-10-07  0:09 ` [PATCH 4/9] of: add self parameter to __of_sysfs_remove_bin_file() Zev Weiss
2021-10-07  5:25   ` Greg Kroah-Hartman
2021-10-07  0:09 ` [PATCH 5/9] of: add self parameter to of_update_property() Zev Weiss
2021-10-07  5:26   ` Greg Kroah-Hartman
2021-10-07  0:09 ` [PATCH 6/9] of: add support for 'dynamic' DT property Zev Weiss
2021-10-08 18:51   ` Frank Rowand
2021-10-08 19:19     ` Frank Rowand
2021-10-11 13:58     ` Frank Rowand
2021-10-11 14:46       ` Frank Rowand
2021-10-11 17:35       ` Zev Weiss
2021-10-07  0:09 ` [PATCH 7/9] of: make OF_DYNAMIC selectable independently of OF_UNITTEST Zev Weiss
2021-10-08 19:01   ` Frank Rowand
2021-10-07  0:09 ` [PATCH 8/9] dt-bindings: document new 'dynamic' common property Zev Weiss
2021-10-07  5:26   ` Greg Kroah-Hartman
2021-10-07  6:03     ` Zev Weiss
2021-10-07  0:09 ` [PATCH 9/9] ARM: dts: aspeed: Add e3c246d4i BIOS flash device Zev Weiss
2021-10-07  2:46 ` [PATCH 0/9] Dynamic DT device nodes Florian Fainelli
2021-10-07  5:44   ` Zev Weiss
2021-10-07  7:04 ` Andy Shevchenko
2021-10-07  9:05   ` Zev Weiss
2021-10-07 10:31     ` Greg Kroah-Hartman
2021-10-07 15:41       ` Zev Weiss
2021-10-07 20:03         ` Rob Herring
2021-10-08  5:41           ` Greg Kroah-Hartman
2021-10-08 19:43           ` Frank Rowand

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