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Message-Id: <20090714140301.25993.97749.sendpatchset@ahunter-tower>
Date: Tue, 14 Jul 2009 17:03:01 +0300
From: Adrian Hunter <adrian.hunter@...ia.com>
To: Andrew.Morton.akpm@...ux-foundation.org,
Andreas.Dilger.adilger@....com, Stephen.Tweedie.sct@...hat.com
Cc: Adrian Hunter <adrian.hunter@...ia.com>,
linux-ext4@...r.kernel.org,
Artem Bityutskiy <artem.bityutskiy@...ia.com>
Subject: [PATCH 1/2] HACK: ext3: mount fast even when recovering
>From 40c3dac03ac40d03d987b2b1385ab3e68277067b Mon Sep 17 00:00:00 2001
From: Adrian Hunter <adrian.hunter@...ia.com>
Date: Fri, 3 Jul 2009 15:25:13 +0300
Subject: [PATCH] HACK: ext3: mount fast even when recovering
Speed up ext3 recovery mount time by not sync'ing the
block device. Instead place all dirty buffers into the
I/O queue and add a write barrier. This ensures that
no subsequent write will reach the disk before all the
recovery writes, but that we do not have to wait for the
I/O.
Note that ext3 reads sectors the correct way: through the
buffer cache, so there is no risk of reading old metadata.
Signed-off-by: Adrian Hunter <adrian.hunter@...ia.com>
---
fs/ext3/super.c | 66 ++++++++++++++++++++++++++++++++++++++++++----
fs/jbd/journal.c | 23 ++++++++++++----
fs/jbd/recovery.c | 19 +++++++++++++-
include/linux/ext3_fs.h | 1 +
include/linux/jbd.h | 1 +
5 files changed, 97 insertions(+), 13 deletions(-)
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index f4be66e..59efefb 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1263,7 +1263,13 @@ static int ext3_setup_super(struct super_block *sb, struct ext3_super_block *es,
ext3_update_dynamic_rev(sb);
EXT3_SET_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER);
- ext3_commit_super(sb, es, 1);
+ /*
+ * If we are in a hurry, we do not need to wait for the super block to
+ * reach the disk. We just need to make sure that all previous writes
+ * arrive before it. Setting the sync parameter to 2 will cause a
+ * write barrier to be added but will not wait for the I/O to complete.
+ */
+ ext3_commit_super(sb, es, test_opt(sb, FAST) ? 2 : 1);
if (test_opt(sb, DEBUG))
printk(KERN_INFO "[EXT3 FS bs=%lu, gc=%lu, "
"bpg=%lu, ipg=%lu, mo=%04lx]\n",
@@ -1622,6 +1628,14 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
set_opt(sbi->s_mount_opt, RESERVATION);
+ /*
+ * Set an option to indicate that we want to mount fast even
+ * when recovering. That is achieved by not sync'ing the
+ * block device, but instead placing all dirty buffers into
+ * the I/O queue and adding a write barrier.
+ */
+ set_opt(sbi->s_mount_opt, FAST);
+
if (!parse_options ((char *) data, sb, &journal_inum, &journal_devnum,
NULL, 0))
goto failed_mount;
@@ -2007,6 +2021,12 @@ static void ext3_init_journal_params(struct super_block *sb, journal_t *journal)
journal->j_flags |= JFS_ABORT_ON_SYNCDATA_ERR;
else
journal->j_flags &= ~JFS_ABORT_ON_SYNCDATA_ERR;
+ /*
+ * Tell the journal about our fast mounting scheme, so it can
+ * play its part.
+ */
+ if (test_opt(sb, FAST))
+ journal->j_flags |= JFS_LOAD_FAST;
spin_unlock(&journal->j_state_lock);
}
@@ -2224,7 +2244,13 @@ static int ext3_load_journal(struct super_block *sb,
mark_sb_dirty(sb);
/* Make sure we flush the recovery flag to disk. */
- ext3_commit_super(sb, es, 1);
+ /*
+ * The super gets committed later by 'ext3_setup_super()'
+ * or 'ext3_maek_recovery_complete()' anyway, so if we are
+ * in a hurry we can skip it here.
+ */
+ if (!test_opt(sb, FAST))
+ ext3_commit_super(sb, es, 1);
}
return 0;
@@ -2285,7 +2311,16 @@ static void ext3_commit_super (struct super_block * sb,
es->s_free_inodes_count = cpu_to_le32(ext3_count_free_inodes(sb));
BUFFER_TRACE(sbh, "marking dirty");
mark_buffer_dirty(sbh);
- if (sync)
+ if (sync == 2) {
+ /*
+ * Caller has requested that a barrier is used, so that this
+ * write will not reach the disk before any previous ones,
+ * and we will not have to wait for it either.
+ */
+ set_buffer_ordered(sbh);
+ ll_rw_block(SWRITE, 1, &sbh);
+ clear_buffer_ordered(sbh);
+ } else if (sync)
sync_dirty_buffer(sbh);
}
@@ -2301,15 +2336,29 @@ static void ext3_mark_recovery_complete(struct super_block * sb,
journal_t *journal = EXT3_SB(sb)->s_journal;
journal_lock_updates(journal);
- if (journal_flush(journal) < 0)
+
+ /*
+ * There is no need to flush the journal so skip it if we are in a
+ * hurry.
+ */
+ if (!test_opt(sb, FAST) && journal_flush(journal) < 0)
goto out;
lock_super(sb);
if (EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER) &&
sb->s_flags & MS_RDONLY) {
+ /*
+ * If we are in a hurry, we do not need to wait for the super
+ * block to reach the disk. We just need to make sure that
+ * all previous writes arrive before it. Setting the sync
+ * parameter to 2 will cause a write barrier to be added but
+ * will not wait for the I/O to complete.
+ */
+ int sync = test_opt(sb, FAST) ? 2 : 1;
+
EXT3_CLEAR_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_RECOVER);
mark_sb_clean(sb);
- ext3_commit_super(sb, es, 1);
+ ext3_commit_super(sb, es, sync);
}
unlock_super(sb);
@@ -2348,7 +2397,12 @@ static void ext3_clear_journal_err(struct super_block * sb,
EXT3_SB(sb)->s_mount_state |= EXT3_ERROR_FS;
es->s_state |= cpu_to_le16(EXT3_ERROR_FS);
- ext3_commit_super (sb, es, 1);
+ /*
+ * The super gets committed later by 'ext3_setup_super()'
+ * anyway, so if we are in a hurry we can skip it here.
+ */
+ if (!test_opt(sb, FAST))
+ ext3_commit_super (sb, es, 1);
journal_clear_err(journal);
}
diff --git a/fs/jbd/journal.c b/fs/jbd/journal.c
index 9e4fa52..3fd14ef 100644
--- a/fs/jbd/journal.c
+++ b/fs/jbd/journal.c
@@ -822,7 +822,7 @@ static void journal_fail_superblock (journal_t *journal)
* subsequent use.
*/
-static int journal_reset(journal_t *journal)
+static int journal_reset(journal_t *journal, int wait)
{
journal_superblock_t *sb = journal->j_superblock;
unsigned long first, last;
@@ -844,7 +844,7 @@ static int journal_reset(journal_t *journal)
journal->j_max_transaction_buffers = journal->j_maxlen / 4;
/* Add the dynamic fields and write it to disk. */
- journal_update_superblock(journal, 1);
+ journal_update_superblock(journal, wait);
return journal_start_thread(journal);
}
@@ -916,13 +916,14 @@ int journal_create(journal_t *journal)
journal->j_flags &= ~JFS_ABORT;
journal->j_format_version = 2;
- return journal_reset(journal);
+ return journal_reset(journal, 1);
}
/**
* void journal_update_superblock() - Update journal sb on disk.
* @journal: The journal to update.
* @wait: Set to '0' if you don't want to wait for IO completion.
+ * Note that a write barrier is used in that case.
*
* Update a journal's dynamic superblock fields and write it to disk,
* optionally waiting for the IO to complete.
@@ -961,8 +962,11 @@ void journal_update_superblock(journal_t *journal, int wait)
mark_buffer_dirty(bh);
if (wait)
sync_dirty_buffer(bh);
- else
+ else {
+ set_buffer_ordered(bh);
ll_rw_block(SWRITE, 1, &bh);
+ clear_buffer_ordered(bh);
+ }
out:
/* If we have just flushed the log (by marking s_start==0), then
@@ -1073,7 +1077,7 @@ static int load_superblock(journal_t *journal)
*/
int journal_load(journal_t *journal)
{
- int err;
+ int err, wait;
journal_superblock_t *sb;
err = load_superblock(journal);
@@ -1103,7 +1107,14 @@ int journal_load(journal_t *journal)
/* OK, we've finished with the dynamic journal bits:
* reinitialise the dynamic contents of the superblock in memory
* and reset them on disk. */
- if (journal_reset(journal))
+ /*
+ * If we are in a hurry, tell the reset not to wait, which will
+ * cause the journal superblock buffer to be placed into the I/O
+ * queue with a barrier, but we will not wait for the I/O to
+ * complete.
+ */
+ wait = journal->j_flags & JFS_LOAD_FAST ? 0 : 1;
+ if (journal_reset(journal, wait))
goto recovery_error;
journal->j_flags &= ~JFS_ABORT;
diff --git a/fs/jbd/recovery.c b/fs/jbd/recovery.c
index db5e982..a245c36 100644
--- a/fs/jbd/recovery.c
+++ b/fs/jbd/recovery.c
@@ -261,7 +261,24 @@ int journal_recover(journal_t *journal)
journal->j_transaction_sequence = ++info.end_transaction;
journal_clear_revoke(journal);
- err2 = sync_blockdev(journal->j_fs_dev);
+ /*
+ * We can massively speed-up the recovery mount time by avoiding
+ * synchronizing the block device. Instead, we just throw all the
+ * dirty buffers into the I/O queue, and rely on callers to add
+ * a write barrier.
+ */
+ if (journal->j_flags & JFS_LOAD_FAST) {
+ struct block_device *bdev = journal->j_fs_dev;
+
+ err2 = 0;
+ if (bdev) {
+ struct address_space *mapping = bdev->bd_inode->i_mapping;
+
+ if (mapping->nrpages)
+ err2 = filemap_fdatawrite(mapping);
+ }
+ } else
+ err2 = sync_blockdev(journal->j_fs_dev);
if (!err)
err = err2;
diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
index d14f029..117e7a1 100644
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -382,6 +382,7 @@ struct ext3_inode {
#define EXT3_MOUNT_GRPQUOTA 0x200000 /* "old" group quota */
#define EXT3_MOUNT_DATA_ERR_ABORT 0x400000 /* Abort on file data write
* error in ordered mode */
+#define EXT3_MOUNT_FAST 0x800000 /* Do not sync during recovery */
/* Compatibility, for having both ext2_fs.h and ext3_fs.h included at once */
#ifndef _LINUX_EXT2_FS_H
diff --git a/include/linux/jbd.h b/include/linux/jbd.h
index 346e2b8..06459ca 100644
--- a/include/linux/jbd.h
+++ b/include/linux/jbd.h
@@ -819,6 +819,7 @@ struct journal_s
#define JFS_ABORT_ON_SYNCDATA_ERR 0x040 /* Abort the journal on file
* data write error in ordered
* mode */
+#define JFS_LOAD_FAST 0x080 /* Do not sync during recovery */
/*
* Function declarations for the journaling transaction and buffer
--
1.5.6.3
--
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