FAILED: patch "[PATCH] ext4: sysfs: print ext4_super_block fields as little-endian" failed to apply to 3.18-stable tree

PATCH [email protected] 1 participant 1 message Aug 30, 2018

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Stable branch ext4 file system

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2018-08-30 21:05 UTC #0 lore raw

The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From a4d2aadca184ece182418950d45ba4ffc7b652d2 Mon Sep 17 00:00:00 2001

From: Arnd Bergmann <[email protected]>
Date: Sun, 29 Jul 2018 15:48:00 -0400
Subject: [PATCH] ext4: sysfs: print ext4_super_block fields as little-endian

While working on extended rand for last_error/first_error timestamps, I noticed that the endianess is wrong; we access the little-endian fields in struct ext4_super_block as native-endian when we print them.

This adds a special case in ext4_attr_show() and ext4_attr_store() to byteswap the superblock fields if needed.

In older kernels, this code was part of super.c, it got moved to sysfs.c in linux-4.4.

Cc [email protected]

Fixes 52c198c6820f ("ext4: add sysfs entry showing whether the fs contains errors")

Reviewed-by Andreas Dilger <[email protected]>

Signed-off-by Arnd Bergmann <[email protected]>

Signed-off-by Theodore Ts'o <[email protected]>

fs/ext4/sysfs.c +10 -3

index f34da0bb8f17..b970a200f20c 100644
@@ -274,8 +274,12 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
 	case attr_pointer_ui:
 		if (!ptr)
 			return 0;
-		return snprintf(buf, PAGE_SIZE, "%u\n",
-				*((unsigned int *) ptr));
+		if (a->attr_ptr == ptr_ext4_super_block_offset)
+			return snprintf(buf, PAGE_SIZE, "%u\n",
+					le32_to_cpup(ptr));
+		else
+			return snprintf(buf, PAGE_SIZE, "%u\n",
+					*((unsigned int *) ptr));
 	case attr_pointer_atomic:
 		if (!ptr)
 			return 0;

@@ -308,7 +312,10 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
 		ret = kstrtoul(skip_spaces(buf), 0, &t);
 		if (ret)
 			return ret;
-		*((unsigned int *) ptr) = t;
+		if (a->attr_ptr == ptr_ext4_super_block_offset)
+			*((__le32 *) ptr) = cpu_to_le32(t);
+		else
+			*((unsigned int *) ptr) = t;
 		return len;
 	case attr_inode_readahead:
 		return inode_readahead_blks_store(sbi, buf, len);