[PATCH] libext2fs: try to get physical sector size first in ext2fs_get_device_sectsize()

[Eric Sandeen <sandeen@redhat.com>]

Some devices, notably 4k sector drives, may have a 512 logical
sector size, mapped onto a 4k physical sector size.

When mke2fs is ratcheting down the blocksize for small filesystems,
or when a blocksize is specified on the commandline, we should not
willingly go below the physical sector size of the device.

When a blocksize is specified, we -must- not go below
the logical sector size of the device.

Add a new library function, ext2fs_get_device_phys_sectsize()
to get the physical sector size if possible, and adjust the
logic in mke2fs to enforce the above rules.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---


diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 213a819..9c06048 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1086,6 +1086,7 @@ extern errcode_t ext2fs_get_device_size2(const char *file, int blocksize,
 
 /* getsectsize.c */
 errcode_t ext2fs_get_device_sectsize(const char *file, int *sectsize);
+errcode_t ext2fs_get_device_phys_sectsize(const char *file, int *sectsize);
 
 /* i_block.c */
 errcode_t ext2fs_iblk_add_blocks(ext2_filsys fs, struct ext2_inode *inode,
diff --git a/lib/ext2fs/getsectsize.c b/lib/ext2fs/getsectsize.c
index ae9139d..0c7fa82 100644
--- a/lib/ext2fs/getsectsize.c
+++ b/lib/ext2fs/getsectsize.c
@@ -26,15 +26,20 @@
 #include <linux/fd.h>
 #endif
 
-#if defined(__linux__) && defined(_IO) && !defined(BLKSSZGET)
+#if defined(__linux__) && defined(_IO)
+#if !defined(BLKSSZGET)
 #define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
 #endif
+#if !defined(BLKPBSZGET)
+#define BLKPBSZGET _IO(0x12,123)/* get block physical sector size */
+#endif
+#endif
 
 #include "ext2_fs.h"
 #include "ext2fs.h"
 
 /*
- * Returns the number of blocks in a partition
+ * Returns the logical sector size of a device 
  */
 errcode_t ext2fs_get_device_sectsize(const char *file, int *sectsize)
 {
@@ -58,3 +63,29 @@ errcode_t ext2fs_get_device_sectsize(const char *file, int *sectsize)
 	close(fd);
 	return 0;
 }
+
+/*
+ * Returns the physical sector size of a device 
+ */
+errcode_t ext2fs_get_device_phys_sectsize(const char *file, int *sectsize)
+{
+	int	fd;
+
+#ifdef HAVE_OPEN64
+	fd = open64(file, O_RDONLY);
+#else
+	fd = open(file, O_RDONLY);
+#endif
+	if (fd < 0)
+		return errno;
+
+#ifdef BLKPBSZGET
+	if (ioctl(fd, BLKPBSZGET, sectsize) >= 0) {
+		close(fd);
+		return 0;
+	}
+#endif
+	*sectsize = 0;
+	close(fd);
+	return 0;
+}
diff --git a/lib/ext2fs/tst_getsectsize.c b/lib/ext2fs/tst_getsectsize.c
index cb1b8c6..31599d2 100644
--- a/lib/ext2fs/tst_getsectsize.c
+++ b/lib/ext2fs/tst_getsectsize.c
@@ -27,7 +27,7 @@
 
 int main(int argc, char **argv)
 {
-	int	sectsize;
+	int	lsectsize, psectsize;
 	int	retval;
 
 	if (argc < 2) {
@@ -35,13 +35,19 @@ int main(int argc, char **argv)
 		exit(1);
 	}
 
-	retval = ext2fs_get_device_sectsize(argv[1], &sectsize);
+	retval = ext2fs_get_device_sectsize(argv[1], &lsectsize);
 	if (retval) {
 		com_err(argv[0], retval,
 			"while calling ext2fs_get_device_sectsize");
 		exit(1);
 	}
-	printf("Device %s has a hardware sector size of %d.\n",
-	       argv[1], sectsize);
+	retval = ext2fs_get_device_phys_sectsize(argv[1], &psectsize);
+	if (retval) {
+		com_err(argv[0], retval,
+			"while calling ext2fs_get_device_phys_sectsize");
+		exit(1);
+	}
+	printf("Device %s has logical/physical sector size of %d/%d.\n",
+	       argv[1], lsectsize, psectsize);
 	exit(0);
 }
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 94b4c81..1a1307b 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -1068,7 +1068,7 @@ static void PRS(int argc, char *argv[])
 	int		inode_size = 0;
 	unsigned long	flex_bg_size = 0;
 	double		reserved_ratio = 5.0;
-	int		sector_size = 0;
+	int		lsector_size = 0, psector_size = 0;
 	int		show_version_only = 0;
 	unsigned long long num_inodes = 0; /* unsigned long long to catch too-large input */
 	errcode_t	retval;
@@ -1586,16 +1586,25 @@ got_size:
 	    ((tmp = getenv("MKE2FS_FIRST_META_BG"))))
 		fs_param.s_first_meta_bg = atoi(tmp);
 
-	/* Get the hardware sector size, if available */
-	retval = ext2fs_get_device_sectsize(device_name, &sector_size);
+	/* Get the hardware sector sizes, if available */
+	retval = ext2fs_get_device_sectsize(device_name, &lsector_size);
 	if (retval) {
 		com_err(program_name, retval,
 			_("while trying to determine hardware sector size"));
 		exit(1);
 	}
+	retval = ext2fs_get_device_phys_sectsize(device_name, &psector_size);
+	if (retval) {
+		com_err(program_name, retval,
+			_("while trying to determine physical sector size"));
+		exit(1);
+	}
+	/* Older kernels may not have physical/logical distinction */
+	if (!psector_size)
+		psector_size = lsector_size;
 
 	if ((tmp = getenv("MKE2FS_DEVICE_SECTSIZE")) != NULL)
-		sector_size = atoi(tmp);
+		psector_size = atoi(tmp);
 
 	if (blocksize <= 0) {
 		use_bsize = get_int_from_profile(fs_types, "blocksize", 4096);
@@ -1606,14 +1615,25 @@ got_size:
 			    (use_bsize > 4096))
 				use_bsize = 4096;
 		}
-		if (sector_size && use_bsize < sector_size)
-			use_bsize = sector_size;
+		if (psector_size && use_bsize < psector_size)
+			use_bsize = psector_size;
 		if ((blocksize < 0) && (use_bsize < (-blocksize)))
 			use_bsize = -blocksize;
 		blocksize = use_bsize;
 		ext2fs_blocks_count_set(&fs_param,
 					ext2fs_blocks_count(&fs_param) /
 					(blocksize / 1024));
+	} else {
+		if (blocksize < lsector_size ||			/* Impossible */
+		    (!force && (blocksize < psector_size))) {	/* Suboptimal */
+			com_err(program_name, EINVAL,
+				_("while setting blocksize; too small for device\n"));
+			exit(1);
+		} else if (blocksize < psector_size) {
+			fprintf(stderr, _("Warning: specified blocksize %d is "
+				"less than device physical sectorsize %d, "
+				"forced to continue\n"), blocksize, psector_size);
+		}
 	}
 
 	if (inode_ratio == 0) {