We introduce a new data write mode known as declared mode. This is based on
ordered mode except that a list of blocks to be written during the current
transaction is added to the journal before the blocks themselves are written to
the disk. Then, if the system crashes, we can resync only those blocks during
journal replay and skip the rest of the resync of the RAID array.
TODO: Add support to e2fsck.
TODO: The following sequence of events could cause resync to be skipped
incorrectly:
- An MD array that supports RESYNC_RANGE is undergoing resync.
- A filesystem on that array is mounted with data=declared.
- The machine crashes before the resync completes.
- The array is restarted and the filesystem is remounted.
- Recovery resyncs only the blocks that were undergoing writes during
the crash and skips the rest.
Addressing this requires even more communication between MD and ext and
I need to think more about how to do this.
Index: linux-2.6.18-128.1.6/fs/ext3/file.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext3/file.c
+++ linux-2.6.18-128.1.6/fs/ext3/file.c
@@ -78,7 +78,8 @@ ext3_file_write(struct kiocb *iocb, cons
* Open question --- do we care about flushing timestamps too
* if the inode is IS_SYNC?
*/
- if (!ext3_should_journal_data(inode))
+ if (!ext3_should_journal_data(inode) &&
+ !ext3_should_declare_data(inode))
return ret;
goto force_commit;
Index: linux-2.6.18-128.1.6/fs/ext3/fsync.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext3/fsync.c
+++ linux-2.6.18-128.1.6/fs/ext3/fsync.c
@@ -66,8 +66,13 @@ int ext3_sync_file(struct file * file, s
* filemap_fdatawait() will encounter a ton of newly-dirtied pages
* (they were dirtied by commit). But that's OK - the blocks are
* safe in-journal, which is all fsync() needs to ensure.
+ *
+ * data=declared:
+ * Declare blocks are written before data blocks, then the
+ * sync proceeds as for data=ordered.
*/
- if (ext3_should_journal_data(inode)) {
+ if (ext3_should_journal_data(inode) ||
+ ext3_should_declare_data(inode)) {
ret = ext3_force_commit(inode->i_sb);
goto out;
}
Index: linux-2.6.18-128.1.6/fs/ext3/inode.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext3/inode.c
+++ linux-2.6.18-128.1.6/fs/ext3/inode.c
@@ -1190,6 +1190,15 @@ static int commit_write_fn(handle_t *han
return ext3_journal_dirty_metadata(handle, bh);
}
+/* For commit_write() in data=declared mode */
+static int declared_commit_write_fn(handle_t *handle, struct buffer_head *bh)
+{
+ if (!buffer_mapped(bh) || buffer_freed(bh))
+ return 0;
+ set_buffer_uptodate(bh);
+ return ext3_journal_dirty_data(handle, bh);
+}
+
/*
* We need to pick up the new inode size which generic_commit_write gave us
* `file' can be NULL - eg, when called from page_symlink().
@@ -1220,6 +1229,37 @@ static int ext3_ordered_commit_write(str
EXT3_I(inode)->i_disksize = new_i_size;
ret = generic_commit_write(file, page, from, to);
}
+
+ ret2 = ext3_journal_stop(handle);
+ if (!ret)
+ ret = ret2;
+ return ret;
+}
+
+static int ext3_declared_commit_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ handle_t *handle = ext3_journal_current_handle();
+ struct inode *inode = page->mapping->host;
+ int ret = 0, ret2;
+ int partial = 0;
+ loff_t pos;
+
+ ret = walk_page_buffers(handle, page_buffers(page),
+ from, to, &partial, declared_commit_write_fn);
+
+ if (ret == 0) {
+ pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+ if (pos > EXT3_I(inode)->i_disksize)
+ EXT3_I(inode)->i_disksize = pos;
+ if (!partial)
+ SetPageUptodate(page);
+ if (pos > inode->i_size) {
+ i_size_write(inode, pos);
+ mark_inode_dirty(inode);
+ }
+ }
+
ret2 = ext3_journal_stop(handle);
if (!ret)
ret = ret2;
@@ -1741,14 +1781,30 @@ static const struct address_space_operat
.releasepage = ext3_releasepage,
};
+static const struct address_space_operations ext3_declared_aops = {
+ .readpage = ext3_readpage,
+ .readpages = ext3_readpages,
+ .writepage = ext3_ordered_writepage,
+ .sync_page = block_sync_page,
+ .prepare_write = ext3_prepare_write,
+ .commit_write = ext3_declared_commit_write,
+ .bmap = ext3_bmap,
+ .invalidatepage = ext3_invalidatepage,
+ .releasepage = ext3_releasepage,
+ .direct_IO = ext3_direct_IO,
+ .migratepage = buffer_migrate_page,
+};
+
void ext3_set_aops(struct inode *inode)
{
if (ext3_should_order_data(inode))
inode->i_mapping->a_ops = &ext3_ordered_aops;
else if (ext3_should_writeback_data(inode))
inode->i_mapping->a_ops = &ext3_writeback_aops;
- else
+ else if (ext3_should_journal_data(inode))
inode->i_mapping->a_ops = &ext3_journalled_aops;
+ else
+ inode->i_mapping->a_ops = &ext3_declared_aops;
}
/*
@@ -1845,9 +1901,12 @@ static int ext3_block_truncate_page(hand
if (ext3_should_journal_data(inode)) {
err = ext3_journal_dirty_metadata(handle, bh);
} else {
- if (ext3_should_order_data(inode))
+ if (ext3_should_order_data(inode) ||
+ ext3_should_declare_data(inode))
err = ext3_journal_dirty_data(handle, bh);
- mark_buffer_dirty(bh);
+
+ if (!ext3_should_declare_data(inode))
+ mark_buffer_dirty(bh);
}
unlock:
Index: linux-2.6.18-128.1.6/fs/ext3/super.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext3/super.c
+++ linux-2.6.18-128.1.6/fs/ext3/super.c
@@ -391,6 +391,9 @@ static void ext3_put_super (struct super
int i, err;
ext3_xattr_put_super(sb);
+ journal_clear_features(sbi->s_journal, 0, 0,
+ JFS_FEATURE_INCOMPAT_DECLARE_BLOCKS);
+ journal_update_superblock(sbi->s_journal, 1);
err = journal_destroy(sbi->s_journal);
sbi->s_journal = NULL;
if (err < 0)
@@ -553,6 +556,8 @@ static int ext3_show_options(struct seq_
seq_puts(seq, ",data=ordered");
else if (test_opt(sb, DATA_FLAGS) == EXT3_MOUNT_WRITEBACK_DATA)
seq_puts(seq, ",data=writeback");
+ else if (test_opt(sb, DATA_FLAGS) == EXT3_MOUNT_DECLARED_DATA)
+ seq_puts(seq, ",data=declared");
ext3_show_quota_options(seq, sb);
@@ -682,7 +687,7 @@ enum {
Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
- Opt_grpquota
+ Opt_grpquota, Opt_data_declared
};
static match_table_t tokens = {
@@ -721,6 +726,7 @@ static match_table_t tokens = {
{Opt_data_journal, "data=journal"},
{Opt_data_ordered, "data=ordered"},
{Opt_data_writeback, "data=writeback"},
+ {Opt_data_declared, "data=declared"},
{Opt_offusrjquota, "usrjquota="},
{Opt_usrjquota, "usrjquota=%s"},
{Opt_offgrpjquota, "grpjquota="},
@@ -922,6 +928,9 @@ static int parse_options (char *options,
goto datacheck;
case Opt_data_writeback:
data_opt = EXT3_MOUNT_WRITEBACK_DATA;
+ goto datacheck;
+ case Opt_data_declared:
+ data_opt = EXT3_MOUNT_DECLARED_DATA;
datacheck:
if (is_remount) {
if ((sbi->s_mount_opt & EXT3_MOUNT_DATA_FLAGS)
@@ -1740,7 +1749,21 @@ static int ext3_fill_super (struct super
else
set_opt(sbi->s_mount_opt, JOURNAL_DATA);
break;
-
+ case EXT3_MOUNT_DECLARED_DATA:
+ if (!journal_check_available_features
+ (sbi->s_journal, 0, 0, JFS_FEATURE_INCOMPAT_DECLARE_BLOCKS)) {
+ printk(KERN_ERR "EXT3-fs: Journal does not support "
+ "declared data journaling mode\n");
+ goto failed_mount4;
+ }
+ spin_lock(&sbi->s_journal->j_state_lock);
+ sbi->s_journal->j_flags |= JFS_DECLARE;
+ spin_unlock(&sbi->s_journal->j_state_lock);
+ if (!journal_set_features(sbi->s_journal, 0, 0,
+ JFS_FEATURE_INCOMPAT_DECLARE_BLOCKS)) {
+ printk(KERN_ERR "EXT3-fs: Cannot set declared mode.\n");
+ goto failed_mount4;
+ }
case EXT3_MOUNT_ORDERED_DATA:
case EXT3_MOUNT_WRITEBACK_DATA:
if (!journal_check_available_features
@@ -1797,6 +1820,7 @@ static int ext3_fill_super (struct super
printk (KERN_INFO "EXT3-fs: mounted filesystem with %s data mode.\n",
test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_JOURNAL_DATA ? "journal":
test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_ORDERED_DATA ? "ordered":
+ test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_DECLARED_DATA ? "declared":
"writeback");
lock_kernel();
Index: linux-2.6.18-128.1.6/include/linux/ext3_fs.h
===================================================================
--- linux-2.6.18-128.1.6.orig/include/linux/ext3_fs.h
+++ linux-2.6.18-128.1.6/include/linux/ext3_fs.h
@@ -357,11 +357,11 @@ struct ext3_inode {
#define EXT3_MOUNT_MINIX_DF 0x00080 /* Mimics the Minix statfs */
#define EXT3_MOUNT_NOLOAD 0x00100 /* Don't use existing journal*/
#define EXT3_MOUNT_ABORT 0x00200 /* Fatal error detected */
-#define EXT3_MOUNT_DATA_FLAGS 0x00C00 /* Mode for data writes: */
+#define EXT3_MOUNT_DATA_FLAGS 0x01C00 /* Mode for data writes: */
#define EXT3_MOUNT_JOURNAL_DATA 0x00400 /* Write data to journal */
#define EXT3_MOUNT_ORDERED_DATA 0x00800 /* Flush data before commit */
#define EXT3_MOUNT_WRITEBACK_DATA 0x00C00 /* No data ordering */
-#define EXT3_MOUNT_UPDATE_JOURNAL 0x01000 /* Update the journal format */
+#define EXT3_MOUNT_DECLARED_DATA 0x01000 /* Declare data blocks before writing */
#define EXT3_MOUNT_NO_UID32 0x02000 /* Disable 32-bit UIDs */
#define EXT3_MOUNT_XATTR_USER 0x04000 /* Extended user attributes */
#define EXT3_MOUNT_POSIX_ACL 0x08000 /* POSIX Access Control Lists */
@@ -383,6 +383,7 @@ struct ext3_inode {
#define EXT2_MOUNT_ABORT EXT3_MOUNT_ABORT
#define EXT2_MOUNT_DATA_FLAGS EXT3_MOUNT_DATA_FLAGS
#endif
+#define EXT3_MOUNT_UPDATE_JOURNAL 0x40000000 /* Update the journal format */
#define ext3_set_bit ext2_set_bit
#define ext3_set_bit_atomic ext2_set_bit_atomic
Index: linux-2.6.18-128.1.6/include/linux/ext3_jbd.h
===================================================================
--- linux-2.6.18-128.1.6.orig/include/linux/ext3_jbd.h
+++ linux-2.6.18-128.1.6/include/linux/ext3_jbd.h
@@ -265,4 +265,15 @@ static inline int ext3_should_writeback_
return 0;
}
+static inline int ext3_should_declare_data(struct inode *inode)
+{
+ if (!S_ISREG(inode->i_mode))
+ return 0;
+ if (EXT3_I(inode)->i_flags & EXT3_JOURNAL_DATA_FL)
+ return 0;
+ if (test_opt(inode->i_sb, DATA_FLAGS) == EXT3_MOUNT_DECLARED_DATA)
+ return 1;
+ return 0;
+}
+
#endif /* _LINUX_EXT3_JBD_H */
--
--
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