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Date:   Thu, 6 Feb 2020 17:52:52 -0500
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: EXT4: unsupported inode size: 4096
Message-ID: <20200206225252.GA3673@mit.edu>
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On Thu, Feb 06, 2020 at 04:35:42PM +0100, Herbert Poetzl wrote:
> 
> I recently updated one of my servers from an older 4.19
> Linux kernel to the latest 5.5 kernel mainly because of 
> the many filesystem improvements, just to find that some
> of my filesystems simply cannot be mounted anymore.

Thanks for the bug report!  This was actually a regression caused by
recent security fix (which landed after 5.5, but which backported to
the 5.5 stable kernel).

The following should fix things.  Please let me know if you still have
problems after applying this fix.

					- Ted


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	filename="0001-ext4-fix-support-for-inode-sizes-1024-bytes.patch"

From e0c963ab41e21bea32565a36654523687be3e7f0 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 6 Feb 2020 17:35:01 -0500
Subject: [PATCH] ext4: fix support for inode sizes > 1024 bytes

A recent commit, 9803387c55f7 ("ext4: validate the
debug_want_extra_isize mount option at parse time"), moved mount-time
checks around.  One of those changes moved the inode size check before
the blocksize variable was set to the blocksize of the file system.
After 9803387c55f7 was set to the minimum allowable blocksize, which
in practice on most systems would be 1024 bytes.  This cuased file
systems with inode sizes larger than 1024 bytes to be rejected with a
message:

EXT4-fs (sdXX): unsupported inode size: 4096

Fixes: 9803387c55f7 ("ext4: validate the debug_want_extra_isize mount option at parse time")
Cc: stable@kernel.org
Reported-by: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/super.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 88b213bd32bc..eebcf9b9272d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3814,6 +3814,15 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 */
 	sbi->s_li_wait_mult = EXT4_DEF_LI_WAIT_MULT;
 
+	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
+	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
+	    blocksize > EXT4_MAX_BLOCK_SIZE) {
+		ext4_msg(sb, KERN_ERR,
+		       "Unsupported filesystem blocksize %d (%d log_block_size)",
+			 blocksize, le32_to_cpu(es->s_log_block_size));
+		goto failed_mount;
+	}
+
 	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV) {
 		sbi->s_inode_size = EXT4_GOOD_OLD_INODE_SIZE;
 		sbi->s_first_ino = EXT4_GOOD_OLD_FIRST_INO;
@@ -3831,6 +3840,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			ext4_msg(sb, KERN_ERR,
 			       "unsupported inode size: %d",
 			       sbi->s_inode_size);
+			ext4_msg(sb, KERN_ERR, "blocksize: %d", blocksize);
 			goto failed_mount;
 		}
 		/*
@@ -4033,14 +4043,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	if (!ext4_feature_set_ok(sb, (sb_rdonly(sb))))
 		goto failed_mount;
 
-	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);
-	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
-	    blocksize > EXT4_MAX_BLOCK_SIZE) {
-		ext4_msg(sb, KERN_ERR,
-		       "Unsupported filesystem blocksize %d (%d log_block_size)",
-			 blocksize, le32_to_cpu(es->s_log_block_size));
-		goto failed_mount;
-	}
 	if (le32_to_cpu(es->s_log_block_size) >
 	    (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE)) {
 		ext4_msg(sb, KERN_ERR,
-- 
2.24.1


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