linux-kernel - [PATCH] Revert "fat: add simple validation for directory inode"

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Message-Id: <20220204062232.3410036-1-gwendal@chromium.org>
Date:   Thu,  3 Feb 2022 22:22:32 -0800
From:   Gwendal Grignou <gwendal@...omium.org>
To:     hirofumi@...l.parknet.co.jp
Cc:     dlunev@...omium.org, linux-kernel@...r.kernel.org,
        Gwendal Grignou <gwendal@...omium.org>
Subject: [PATCH] Revert "fat: add simple validation for directory inode"

This reverts commit a3082d526f2d406d4b488e49a508a0062a23314f.

The reverted commit adds check for FAT images. However, the tools used
for creating images for the Lego Mindstrom EV3 are not adding '.' and
'..' entry in the 'Projects' directory.
Without this fix, the kernel can not fill the inode structure for
'Projects' directory.

See https://github.com/microsoft/pxt-ev3/issues/980
And https://github.com/microsoft/uf2-linux/issues/6

With the patch reverted, we can mount an image copied from the EV3

Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
---
 fs/fat/inode.c | 22 ----------------------
 1 file changed, 22 deletions(-)

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index a6f1c6d426d1..45c8dcc10547 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -494,24 +494,6 @@ static int fat_calc_dir_size(struct inode *inode)
 	return 0;
 }
 
-static int fat_validate_dir(struct inode *dir)
-{
-	struct super_block *sb = dir->i_sb;
-
-	if (dir->i_nlink < 2) {
-		/* Directory should have "."/".." entries at least. */
-		fat_fs_error(sb, "corrupted directory (invalid entries)");
-		return -EIO;
-	}
-	if (MSDOS_I(dir)->i_start == 0 ||
-	    MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
-		/* Directory should point valid cluster. */
-		fat_fs_error(sb, "corrupted directory (invalid i_start)");
-		return -EIO;
-	}
-	return 0;
-}
-
 /* doesn't deal with root inode */
 int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 {
@@ -538,10 +520,6 @@ int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 		MSDOS_I(inode)->mmu_private = inode->i_size;
 
 		set_nlink(inode, fat_subdirs(inode));
-
-		error = fat_validate_dir(inode);
-		if (error < 0)
-			return error;
 	} else { /* not a directory */
 		inode->i_generation |= 1;
 		inode->i_mode = fat_make_mode(sbi, de->attr,
-- 
2.35.0.263.gb82422642f-goog