linux-ext4 - [PATCH v2 2/2] tune2fs: Warn if page size != blocksize when enabling encrypt

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Message-Id: <20190822121725.22550-1-lczerner@redhat.com>
Date:   Thu, 22 Aug 2019 14:17:25 +0200
From:   Lukas Czerner <lczerner@...hat.com>
To:     linux-ext4@...r.kernel.org
Subject: [PATCH v2 2/2] tune2fs: Warn if page size != blocksize when enabling encrypt

With encrypt feature enabled the file system block size must match
system page size. Currently tune2fs will not complain at all when we try
to enable encrypt on a file system that does not satisfy this
requirement for the system. Add a warning for this case.

Signed-off-by: Lukas Czerner <lczerner@...hat.com>
---
 misc/tune2fs.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 7d2d38d7..f1604447 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -130,6 +130,8 @@ void do_findfs(int argc, char **argv);
 int journal_enable_debug = -1;
 #endif
 
+static int sys_page_size = 4096;
+
 static void usage(void)
 {
 	fprintf(stderr,
@@ -1407,6 +1409,30 @@ mmp_error:
 			      stderr);
 			return 1;
 		}
+
+		/*
+		 * When encrypt feature is enabled, the file system blocksize
+		 * needs to match system page size otherwise the file system
+		 * won't mount.
+		 */
+		if (fs->blocksize != sys_page_size) {
+			if (!f_flag) {
+				com_err(program_name, 0,
+					_("Encryption feature requested, but "
+					  "block size (%dB) does not match "
+					  "system page size (%dB). File "
+					  "system won't be usable on this "
+					  "system"),
+					fs->blocksize, sys_page_size);
+				proceed_question(-1);
+			}
+			fprintf(stderr,_("Warning: Encrypt feature enabled, "
+					 "but block size (%dB) does not match "
+					 "system page size (%dB), forced to "
+					 "cointinue\n"),
+				fs->blocksize, sys_page_size);
+		}
+
 		fs->super->s_encrypt_algos[0] =
 			EXT4_ENCRYPTION_MODE_AES_256_XTS;
 		fs->super->s_encrypt_algos[1] =
@@ -2844,6 +2870,7 @@ int main(int argc, char **argv)
 int tune2fs_main(int argc, char **argv)
 #endif  /* BUILD_AS_LIB */
 {
+	long sysval;
 	errcode_t retval;
 	ext2_filsys fs;
 	struct ext2_super_block *sb;
@@ -2879,6 +2906,18 @@ int tune2fs_main(int argc, char **argv)
 #endif
 		io_ptr = unix_io_manager;
 
+	/* Determine the system page size if possible */
+#ifdef HAVE_SYSCONF
+#if (!defined(_SC_PAGESIZE) && defined(_SC_PAGE_SIZE))
+#define _SC_PAGESIZE _SC_PAGE_SIZE
+#endif
+#ifdef _SC_PAGESIZE
+	sysval = sysconf(_SC_PAGESIZE);
+	if (sysval > 0)
+		sys_page_size = sysval;
+#endif /* _SC_PAGESIZE */
+#endif /* HAVE_SYSCONF */
+
 retry_open:
 	if ((open_flag & EXT2_FLAG_RW) == 0 || f_flag)
 		open_flag |= EXT2_FLAG_SKIP_MMP;
-- 
2.21.0