The patch titled
Subject: fat: remov FAT_FIRST_ENT macro
has been added to the -mm tree. Its filename is
fat-removed-fat_first_ent-macro.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fat-removed-fat_first_ent-macro.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fat-removed-fat_first_ent-macro.patch
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From: Carmeli Tamir <carmeli.tamir@xxxxxxxxx>
Subject: fat: remov FAT_FIRST_ENT macro
The comment edited in this patch was the only reference to the
FAT_FIRST_ENT macro, which is not used anymore. Moreover, the commented
line of code does not compile with the current code.
Since the FAT_FIRST_ENT macro checks the FAT variant in a way that the
patch series changes, I removed it, and instead wrote a clear explanation
of what was checked.
I verified that the changed comment is correct according to Microsoft FAT
spec, search for "BPB_Media" in the following references:
1. Microsoft FAT specification 2005
(http://read.pudn.com/downloads77/ebook/294884/FAT32%20Spec%20%28SDA%20Contribution%29.pdf).
Search for 'volume label'.
2. Microsoft Extensible Firmware Initiative, FAT32 File System Specification
(https://staff.washington.edu/dittrich/misc/fatgen103.pdf).
Search for 'volume label'.
Link: http://lkml.kernel.org/r/1544990640-11604-2-git-send-email-carmeli.tamir@xxxxxxxxx
Signed-off-by: Carmeli Tamir <carmeli.tamir@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fat/inode.c | 12 ++++++++----
include/uapi/linux/msdos_fs.h | 3 ---
2 files changed, 8 insertions(+), 7 deletions(-)
--- a/fs/fat/inode.c~fat-removed-fat_first_ent-macro
+++ a/fs/fat/inode.c
@@ -1803,11 +1803,15 @@ int fat_fill_super(struct super_block *s
fat_ent_access_init(sb);
/*
- * The low byte of FAT's first entry must have same value with
- * media-field. But in real world, too many devices is
- * writing wrong value. So, removed that validity check.
+ * The low byte of the first FAT entry must have the same value as
+ * the media field of the boot sector. But in real world, too many
+ * devices are writing wrong values. So, removed that validity check.
*
- * if (FAT_FIRST_ENT(sb, media) != first)
+ * The removed check compared the first FAT entry to a value dependent
+ * on the media field like this:
+ * == (0x0F00 | media), for FAT12
+ * == (0XFF00 | media), for FAT16
+ * == (0x0FFFFF | media), for FAT32
*/
error = -EINVAL;
--- a/include/uapi/linux/msdos_fs.h~fat-removed-fat_first_ent-macro
+++ a/include/uapi/linux/msdos_fs.h
@@ -58,9 +58,6 @@
#define MSDOS_DOT ". " /* ".", padded to MSDOS_NAME chars */
#define MSDOS_DOTDOT ".. " /* "..", padded to MSDOS_NAME chars */
-#define FAT_FIRST_ENT(s, x) ((MSDOS_SB(s)->fat_bits == 32 ? 0x0FFFFF00 : \
- MSDOS_SB(s)->fat_bits == 16 ? 0xFF00 : 0xF00) | (x))
-
/* start of data cluster's entry (number of reserved clusters) */
#define FAT_START_ENT 2
_
Patches currently in -mm which might be from carmeli.tamir@xxxxxxxxx are
fat-replaced-11-magic-to-msdos_name-for-volume-label.patch
fat-removed-fat_first_ent-macro.patch
fat-moved-max_fat-to-fath-and-changed-it-to-inline-function.patch
fat-new-inline-functions-to-determine-the-fat-variant-32-16-or-12.patch
