[PATCH 1/1 v2 RESEND] mke2fs: check that auto-detected blocksize <= sys_page_size

[PATCH 1/1 v2 RESEND] mke2fs: check that auto-detected blocksize <= sys_page_size

[Yury V. Zaytsev]

Block size can be specified manually via the -b option or deduced
automatically. Unfortunately, the check that it is still smaller than
the system page size is only performed right after the command line
options are parsed.

Therefore, if buggy or inappropriately installed/configured hardware
hints that larger block sizes have to be used, mkfs will silently create
a file system which can not be mounted on the system in question.

By moving the check beyond the last assignment to blocksize it is now
ensured, that mkfs will issue a warning even if inappropriate blocksize
was auto-detected.

The new behavior can be easily tested, by exporting the following
variables before running mkfs:

    export MKE2FS_DEVICE_SECTSIZE=8192
    export MKE2FS_DEVICE_PHYS_SECTSIZE=8192

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
---
 misc/mke2fs.c |   24 +++++++++++++-----------
 1 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index e062bda..3f1b642 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -1514,17 +1514,6 @@ profile_error:
 		ext2fs_close(jfs);
 	}
 
-	if (blocksize > sys_page_size) {
-		if (!force) {
-			com_err(program_name, 0,
-				_("%d-byte blocks too big for system (max %d)"),
-				blocksize, sys_page_size);
-			proceed_question();
-		}
-		fprintf(stderr, _("Warning: %d-byte blocks too big for system "
-				  "(max %d), forced to continue\n"),
-			blocksize, sys_page_size);
-	}
 	if (optind < argc) {
 		fs_blocks_count = parse_num_blocks2(argv[optind++],
 						   fs_param.s_log_block_size);
@@ -1833,6 +1822,19 @@ profile_error:
 
 	blocksize = EXT2_BLOCK_SIZE(&fs_param);
 
+	/* This check should happen beyond the last assignment to blocksize */
+	if (blocksize > sys_page_size) {
+		if (!force) {
+			com_err(program_name, 0,
+				_("%d-byte blocks too big for system (max %d)"),
+				blocksize, sys_page_size);
+			proceed_question();
+		}
+		fprintf(stderr, _("Warning: %d-byte blocks too big for system "
+				  "(max %d), forced to continue\n"),
+			blocksize, sys_page_size);
+	}
+
 	lazy_itable_init = 0;
 	if (access("/sys/fs/ext4/features/lazy_itable_init", R_OK) == 0)
 		lazy_itable_init = 1;
-- 
1.7.6

Re: [PATCH 1/1 v2 RESEND] mke2fs: check that auto-detected blocksize <= sys_page_size

[Ted Ts'o]

On Wed, Aug 10, 2011 at 10:48:43AM +0200, Yury V. Zaytsev wrote:
> Block size can be specified manually via the -b option or deduced
> automatically. Unfortunately, the check that it is still smaller than
> the system page size is only performed right after the command line
> options are parsed.
> 
> Therefore, if buggy or inappropriately installed/configured hardware
> hints that larger block sizes have to be used, mkfs will silently create
> a file system which can not be mounted on the system in question.
> 
> By moving the check beyond the last assignment to blocksize it is now
> ensured, that mkfs will issue a warning even if inappropriate blocksize
> was auto-detected.
> 
> The new behavior can be easily tested, by exporting the following
> variables before running mkfs:
> 
>     export MKE2FS_DEVICE_SECTSIZE=8192
>     export MKE2FS_DEVICE_PHYS_SECTSIZE=8192
> 
> Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
> Reviewed-by: Lukas Czerner <lczerner@redhat.com>

Thanks, I've merged this into the next branch.  Apologies for the delay.

	     	    	      	       - Ted