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55 lines
2.0 KiB
Diff
55 lines
2.0 KiB
Diff
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From b928add95c9ddaa70b591da00d129558535d14d3 Mon Sep 17 00:00:00 2001
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From: Marek Vasut <marex@denx.de>
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Date: Wed, 18 May 2016 16:16:51 +0200
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Subject: [PATCH] configfs: Remove ppos increment in configfs_write_bin_file
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[ Back-port of f8608985f851c917b3884b692d8e326b0210d34e ]
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The simple_write_to_buffer() already increments the @ppos on success,
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see fs/libfs.c simple_write_to_buffer() comment:
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"
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On success, the number of bytes written is returned and the offset @ppos
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advanced by this number, or negative value is returned on error.
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"
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If the configfs_write_bin_file() is invoked with @count smaller than the
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total length of the written binary file, it will be invoked multiple times.
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Since configfs_write_bin_file() increments @ppos on success, after calling
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simple_write_to_buffer(), the @ppos is incremented twice.
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Subsequent invocation of configfs_write_bin_file() will result in the next
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piece of data being written to the offset twice as long as the length of
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the previous write, thus creating buffer with "holes" in it.
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The simple testcase using DTO follows:
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$ mkdir /sys/kernel/config/device-tree/overlays/1
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$ dd bs=1 if=foo.dtbo of=/sys/kernel/config/device-tree/overlays/1/dtbo
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Without this patch, the testcase will result in twice as big buffer in the
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kernel, which is then passed to the cfs_overlay_item_dtbo_write() .
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Signed-off-by: Marek Vasut <marex@denx.de>
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Cc: Geert Uytterhoeven <geert+renesas@glider.be>
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Cc: Christoph Hellwig <hch@lst.de>
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Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
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---
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fs/configfs/file.c | 2 --
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1 file changed, 2 deletions(-)
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diff --git a/fs/configfs/file.c b/fs/configfs/file.c
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index 3687187..6e322f2 100644
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--- a/fs/configfs/file.c
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+++ b/fs/configfs/file.c
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@@ -357,8 +357,6 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
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len = simple_write_to_buffer(buffer->bin_buffer,
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buffer->bin_buffer_size, ppos, buf, count);
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- if (len > 0)
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- *ppos += len;
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out:
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mutex_unlock(&buffer->mutex);
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return len;
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--
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2.1.4
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