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Date:   Thu, 21 Nov 2019 15:03:15 +0300
From:   Artem Blagodarenko <artem.blagodarenko@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     adilger.kernel@...ger.ca, Vladimir Saveliev <c17830@...y.com>
Subject: [REF] LUS-6746 debugfs: fake_fill_fs to fragment filesystem

From: Vladimir Saveliev <c17830@...y.com>

New command is added to debugfs: fake_fill_fs <filling in %>

This command finds free blocks on a filesystem and mark as in use
specified fraction of those.

Example: debugfs -w -R 'fake_fill_fs 50' <device>

This can be to used in order to quickly fragment a filesystem which
may useful for block allocation improvement estimation.

Use it carefully, there is no way to recover free space but using
e2fsck.

Change-Id: Ib7ce7794eefac2726fef334810a5832d52a90398
Signed-off-by: Vladimir Saveliev <c17830@...y.com>
Signed-off-by: Artem Blagodarenko <c17828@...y.com>
Cray-bug-id: LUS-6746
---
 debugfs/debug_cmds.ct |  2 ++
 debugfs/debugfs.c     | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/debugfs/debug_cmds.ct b/debugfs/debug_cmds.ct
index 1ff6c9dc..12557888 100644
--- a/debugfs/debug_cmds.ct
+++ b/debugfs/debug_cmds.ct
@@ -229,5 +229,7 @@ request do_journal_write, "Write a transaction to the journal",
 request do_journal_run, "Recover the journal",
 	journal_run, jr;
 
+request do_fake_fill_fs, "Make the filesystem to look as if it was full",
+	fake_fill_fs;
 end;
 
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 9b701455..25731883 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -2209,6 +2209,36 @@ err:
 	ext2fs_free_mem(&buf);
 }
 
+void do_fake_fill_fs(int argc, char *argv[])
+{
+	__u64 block_count, i;
+	unsigned long v;
+	char *tmp;
+	int f;
+
+	if (common_args_process(argc, argv, 2, 2, argv[0],
+				"filling(%)", CHECK_FS_BITMAPS))
+		return;
+	if (check_fs_read_write(argv[0]))
+		return;
+	v = strtoul(argv[1], &tmp, 0);
+	if (v < 1 || v > 100) {
+		com_err("argv[0]", 0, "filling [1-100]");
+	}
+
+	block_count = ext2fs_blocks_count(current_fs->super);
+	for (i = 1, f = 0; i < block_count; i++) {
+		if (!ext2fs_test_block_bitmap2(current_fs->block_map, i)) {
+			f %= 100;
+			if (f < v)
+				ext2fs_block_alloc_stats2(current_fs, i, +1);
+			f ++;
+		}
+	}
+
+	ext2fs_mark_bb_dirty(current_fs);
+}
+
 #ifndef READ_ONLY
 void do_set_current_time(int argc, char *argv[],
 			 int sci_idx EXT2FS_ATTR((unused)),
-- 
2.14.3 (Apple Git-98)

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