On Wed, Nov 28, 2018 at 02:16:30PM -0700, Andreas Dilger wrote:

quoted

On Nov 28, 2018, at 1:48 PM, Artem Blagodarenko [off-list ref] wrote:

tune2fs is used to make e2label duties.  ext2fs_open2() reads group
descriptors which are not used during disk label obtaining, but
takes a lot of time on large partitions.

This patch change ext2fs_open2(), so only initialized
superblock is returned. without block descriptors. This save
time dramatically.

Cray-bug-id: LUS-5777
Signed-off-by: Artem Blagodarenko <redacted>

One minor nit at the end, but looks fine otherwise:

Reviewed-by: Andreas Dilger <redacted>

quoted

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 5b87d395..2abb6f76 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h

@@ -204,6 +204,7 @@ typedef struct ext2_file *ext2_file_t;

#define EXT2_FLAG_IGNORE_CSUM_ERRORS	0x200000
#define EXT2_FLAG_SHARE_DUP		0x400000
#define EXT2_FLAG_IGNORE_SB_ERRORS	0x800000
+#define EXT2_FLAG_JOURNAL_ONLY		0x1000000

/*
 * Special flag in the ext2 inode i_flag field that means that this is

diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index 85d73e2a..af671070 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c

@@ -135,6 +135,7 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,

	int		j;
#endif
	char		*time_env;
+	unsigned long	enough_desc_blocks;

	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);

@@ -440,12 +441,23 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,

		dest += fs->blocksize*first_meta_bg;
	}

-	for (i = first_meta_bg ; i < fs->desc_blocks; i++) {
+	/*
+	 * Need superblock and journal inode only. Do not read
+	 * met_bg group blocks if journal inode group already loaded
+	 */
+	if (flags & EXT2_FLAG_JOURNAL_ONLY)
+		enough_desc_blocks =
+			fs->super->s_journal_inum /
+			EXT2_INODES_PER_GROUP(fs->super) + 1;
+	else
+		enough_desc_blocks = fs->desc_blocks;
+
+	for (i = first_meta_bg; i < enough_desc_blocks; i++) {
		blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
		io_channel_cache_readahead(fs->io, blk, 1);
	}

-	for (i=first_meta_bg ; i < fs->desc_blocks; i++) {
+	for (i = first_meta_bg; i < enough_desc_blocks; i++) {
		blk = ext2fs_descriptor_block_loc2(fs, group_block, i);
		retval = io_channel_read_blk64(fs->io, blk, 1, dest);
		if (retval)

@@ -468,8 +480,12 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,

	 */
	if (superblock > 1 && ext2fs_has_group_desc_csum(fs)) {
		dgrp_t group;
+		dgrp_t enough_desc_count;
+
+		enough_desc_count = enough_desc_blocks *
+				    EXT2_DESC_PER_BLOCK(fs->super);

-		for (group = 0; group < fs->group_desc_count; group++) {
+		for (group = 0; group < enough_desc_count; group++) {
			ext2fs_bg_flags_clear(fs, group, EXT2_BG_BLOCK_UNINIT);
			ext2fs_bg_flags_clear(fs, group, EXT2_BG_INODE_UNINIT);
			ext2fs_bg_itable_unused_set(fs, group, 0);

diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index cd4057c3..b226fdbf 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c

@@ -2882,6 +2882,12 @@ retry_open:

	/* keep the filesystem struct around to dump MMP data */
	open_flag |= EXT2_FLAG_NOFREE_ON_ERROR;

+	if (print_label || L_flag) {
+		open_flag |= EXT2_FLAG_JOURNAL_ONLY;
+		/* don't want metadata to be flushed at close */
+		//open_flag &= ~EXT2_FLAG_RW;

Might want to remove this ^^^^^ commented out line too...

--D

quoted

+	}
+
	retval = ext2fs_open2(device_name, io_options, open_flag,
			      0, 0, io_ptr, &fs);
	if (retval) {

@@ -2999,7 +3005,6 @@ _("Warning: The journal is dirty. You may wish to replay the journal like:\n\n"

	if ((open_flag & EXT2_FLAG_RW) && !(mount_flags & (EXT2_MF_BUSY | EXT2_MF_MOUNTED)) &&
	    ext2fs_has_feature_journal_needs_recovery(fs->super)) {
		errcode_t err;
-
		printf(_("Recovering journal.\n"));
		err = ext2fs_run_ext3_journal(&fs);
		if (err) {

Not sure why this hunk is here?  There should normally be a blank line after
local variable declarations.

Cheers, Andreas