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Date: Fri, 20 Aug 2010 16:41:14 -0500
From: Eric Sandeen <sandeen@...hat.com>
To: ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH] mke2fs: use lazy inode init on some discard-able devices
If a device supports discard -and- returns 0s for discarded blocks,
then we can skip the inode table initialization -and- the inode table
zeroing at mkfs time, and skip the lazy init as well since they are
already zeroed out.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index add7c0c..b7a9e12 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -88,7 +88,8 @@ int force;
int noaction;
int journal_size;
int journal_flags;
-int lazy_itable_init;
+int lazy_itable_init; /* use lazy inode table init */
+int lazy_itable_zeroed; /* inode table zeroed by discard */
char *bad_blocks_filename;
__u32 fs_stride;
@@ -300,7 +301,7 @@ _("Warning: the backup superblock/group descriptors at block %u contain\n"
ext2fs_badblocks_list_iterate_end(bb_iter);
}
-static void write_inode_tables(ext2_filsys fs, int lazy_flag)
+static void write_inode_tables(ext2_filsys fs, int lazy_flag, int lazy_zeroed)
{
errcode_t retval;
blk64_t blk;
@@ -325,6 +326,9 @@ static void write_inode_tables(ext2_filsys fs, int lazy_flag)
EXT2_INODE_SIZE(fs->super)) +
EXT2_BLOCK_SIZE(fs->super) - 1) /
EXT2_BLOCK_SIZE(fs->super));
+ /* if pre-zeroed by discard, mark as such */
+ if (lazy_zeroed)
+ ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_ZEROED);
} else {
/* The kernel doesn't need to zero the itable blocks */
ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_ZEROED);
@@ -1901,7 +1905,11 @@ static int mke2fs_setup_tdb(const char *name, io_manager *io_ptr)
#define BLKDISCARD _IO(0x12,119)
#endif
-static void mke2fs_discard_blocks(ext2_filsys fs)
+#ifndef BLKDISCARDZEROES
+#define BLKDISCARDZEROES _IO(0x12,124)
+#endif
+
+static int mke2fs_discard_blocks(ext2_filsys fs)
{
int fd;
int ret;
@@ -1917,8 +1925,8 @@ static void mke2fs_discard_blocks(ext2_filsys fs)
fd = open64(fs->device_name, O_RDWR);
/*
- * We don't care about whether the ioctl succeeds; it's only an
- * optmization for SSDs or sparse storage.
+ * We don't much care about whether the ioctl succeeds; it's only
+ * an optmization for SSDs or thinly-provisioned storage.
*/
if (fd > 0) {
ret = ioctl(fd, BLKDISCARD, &range);
@@ -1933,9 +1941,26 @@ static void mke2fs_discard_blocks(ext2_filsys fs)
}
close(fd);
}
+ return ret;
+}
+
+static int mke2fs_discard_zeroes_data(ext2_filsys fs)
+{
+ int fd;
+ int ret;
+ int discard_zeroes_data = 0;
+
+ fd = open64(fs->device_name, O_RDWR);
+
+ if (fd > 0) {
+ ioctl(fd, BLKDISCARDZEROES, &discard_zeroes_data);
+ close(fd);
+ }
+ return discard_zeroes_data;
}
#else
-#define mke2fs_discard_blocks(fs)
+#define mke2fs_discard_blocks(fs) 1
+#define mke2fs_discard_zeroes_data(fs) 0
#endif
int main (int argc, char *argv[])
@@ -1996,8 +2021,17 @@ int main (int argc, char *argv[])
}
/* Can't undo discard ... */
- if (discard && (io_ptr != undo_io_manager))
- mke2fs_discard_blocks(fs);
+ if (discard && (io_ptr != undo_io_manager)) {
+ retval = mke2fs_discard_blocks(fs);
+
+ if (!retval && mke2fs_discard_zeroes_data(fs)) {
+ if (verbose)
+ printf(_("Discard succeeded and will return 0s "
+ " - enabling lazy_itable_init\n"));
+ lazy_itable_init = 1;
+ lazy_itable_zeroed = 1;
+ }
+ }
sprintf(tdb_string, "tdb_data_size=%d", fs->blocksize <= 4096 ?
32768 : fs->blocksize * 8);
@@ -2147,7 +2181,7 @@ int main (int argc, char *argv[])
_("while zeroing block %llu at end of filesystem"),
ret_blk);
}
- write_inode_tables(fs, lazy_itable_init);
+ write_inode_tables(fs, lazy_itable_init, lazy_itable_zeroed);
create_root_dir(fs);
create_lost_and_found(fs);
reserve_inodes(fs);
--
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