[patch 5/8] fs: ext2 inode sync fix

[Nick Piggin]

There is a big fuckup with inode metadata writeback (I suspect in a lot
of filesystems, but I've only dared to look at a couple as yet).

ext2 relies on ->write_inode being called from sync_inode_metadata in
fsync in order to sync the inode. However I_DIRTY_SYNC gets cleared
after a call to this guy, and it doesn't actually write back and wait
on the inode block unless it is called for sync. This means that write_inode
from background writeback can kill the inode dirty bits without the data
getting to disk. Fsync will subsequently miss it.

The fix is for ->write_inode to dirty the buffers/cache, and then ->fsync to
write back the dirty data. In the full filesystem sync case, buffercache
writeback in the generic code will write back the dirty data. Other
filesystems could use ->sync_fs for this.

Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>

Index: linux-2.6/fs/ext2/inode.c
===================================================================
--- linux-2.6.orig/fs/ext2/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/ext2/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -1211,7 +1211,7 @@ static int ext2_setsize(struct inode *in
 	return 0;
 }
 
-static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
+struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
 					struct buffer_head **p)
 {
 	struct buffer_head * bh;
@@ -1505,16 +1505,8 @@ static int __ext2_write_inode(struct ino
 	} else for (n = 0; n < EXT2_N_BLOCKS; n++)
 		raw_inode->i_block[n] = ei->i_data[n];
 	mark_buffer_dirty(bh);
-	if (do_sync) {
-		sync_dirty_buffer(bh);
-		if (buffer_req(bh) && !buffer_uptodate(bh)) {
-			printk ("IO error syncing ext2 inode [%s:%08lx]\n",
-				sb->s_id, (unsigned long) ino);
-			err = -EIO;
-		}
-	}
-	ei->i_state &= ~EXT2_STATE_NEW;
 	brelse (bh);
+	ei->i_state &= ~EXT2_STATE_NEW;
 	return err;
 }
 
Index: linux-2.6/fs/ext2/file.c
===================================================================
--- linux-2.6.orig/fs/ext2/file.c	2010-12-16 18:28:58.000000000 +1100
+++ linux-2.6/fs/ext2/file.c	2010-12-16 18:33:25.000000000 +1100
@@ -21,6 +21,7 @@
 #include <linux/time.h>
 #include <linux/pagemap.h>
 #include <linux/quotaops.h>
+#include <linux/buffer_head.h>
 #include "ext2.h"
 #include "xattr.h"
 #include "acl.h"
@@ -43,16 +44,33 @@ static int ext2_release_file (struct ino
 int ext2_fsync(struct file *file, int datasync)
 {
 	int ret;
-	struct super_block *sb = file->f_mapping->host->i_sb;
-	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
+	struct inode *inode = file->f_mapping->host;
+	ino_t ino = inode->i_ino;
+	struct super_block *sb = inode->i_sb;
+	struct address_space *sb_mapping = sb->s_bdev->bd_inode->i_mapping;
+	struct buffer_head *bh;
+	struct ext2_inode *raw_inode;
 
 	ret = generic_file_fsync(file, datasync);
-	if (ret == -EIO || test_and_clear_bit(AS_EIO, &mapping->flags)) {
+	if (ret == -EIO || test_and_clear_bit(AS_EIO, &sb_mapping->flags)) {
 		/* We don't really know where the IO error happened... */
 		ext2_error(sb, __func__,
 			   "detected IO error when writing metadata buffers");
+		return -EIO;
+	}
+
+	raw_inode = ext2_get_inode(sb, ino, &bh);
+	if (IS_ERR(raw_inode))
+ 		return -EIO;
+
+	sync_dirty_buffer(bh);
+	if (buffer_req(bh) && !buffer_uptodate(bh)) {
+		printk ("IO error syncing ext2 inode [%s:%08lx]\n",
+			sb->s_id, (unsigned long) ino);
 		ret = -EIO;
 	}
+	brelse (bh);
+
 	return ret;
 }
 
Index: linux-2.6/fs/ext2/ext2.h
===================================================================
--- linux-2.6.orig/fs/ext2/ext2.h	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/ext2/ext2.h	2010-12-16 18:33:25.000000000 +1100
@@ -124,6 +124,8 @@ extern int ext2_get_block(struct inode *
 extern int ext2_setattr (struct dentry *, struct iattr *);
 extern void ext2_set_inode_flags(struct inode *inode);
 extern void ext2_get_inode_flags(struct ext2_inode_info *);
+extern struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
+					struct buffer_head **p);
 extern int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		       u64 start, u64 len);
 
Index: linux-2.6/fs/adfs/inode.c
===================================================================
--- linux-2.6.orig/fs/adfs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/adfs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -383,7 +383,7 @@ int adfs_write_inode(struct inode *inode
 	obj.attr	= ADFS_I(inode)->attr;
 	obj.size	= inode->i_size;
 
-	ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
+	ret = adfs_dir_update(sb, &obj, 1 /* XXX: fix fsync and use 'wbc->sync_mode == WB_SYNC_ALL' */);
 	unlock_kernel();
 	return ret;
 }
Index: linux-2.6/fs/affs/file.c
===================================================================
--- linux-2.6.orig/fs/affs/file.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/affs/file.c	2010-12-16 18:33:25.000000000 +1100
@@ -931,6 +931,7 @@ int affs_file_fsync(struct file *filp, i
 	int ret, err;
 
 	ret = write_inode_now(inode, 0);
+	/* XXX: could just sync the buffer been dirtied by write_inode */
 	err = sync_blockdev(inode->i_sb->s_bdev);
 	if (!ret)
 		ret = err;
Index: linux-2.6/fs/bfs/inode.c
===================================================================
--- linux-2.6.orig/fs/bfs/inode.c	2010-12-16 18:29:02.000000000 +1100
+++ linux-2.6/fs/bfs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -151,7 +151,7 @@ static int bfs_write_inode(struct inode
 	di->i_eoffset = cpu_to_le32(i_sblock * BFS_BSIZE + inode->i_size - 1);
 
 	mark_buffer_dirty(bh);
-	if (wbc->sync_mode == WB_SYNC_ALL) {
+	if (1 /* XXX: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */ ) {
 		sync_dirty_buffer(bh);
 		if (buffer_req(bh) && !buffer_uptodate(bh))
 			err = -EIO;
Index: linux-2.6/fs/exofs/inode.c
===================================================================
--- linux-2.6.orig/fs/exofs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/exofs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -1273,7 +1273,7 @@ static int exofs_update_inode(struct ino
 
 int exofs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
-	return exofs_update_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
+	return exofs_update_inode(inode, 1 /* XXX: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */ );
 }
 
 /*
Index: linux-2.6/fs/ext4/inode.c
===================================================================
--- linux-2.6.orig/fs/ext4/inode.c	2010-12-16 18:30:20.000000000 +1100
+++ linux-2.6/fs/ext4/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -5243,7 +5243,7 @@ int ext4_write_inode(struct inode *inode
 		err = __ext4_get_inode_loc(inode, &iloc, 0);
 		if (err)
 			return err;
-		if (wbc->sync_mode == WB_SYNC_ALL)
+		if (1 /* XXX: fix fxync and use wbc->sync_mode == WB_SYNC_ALL */)
 			sync_dirty_buffer(iloc.bh);
 		if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
 			EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
Index: linux-2.6/fs/fat/inode.c
===================================================================
--- linux-2.6.orig/fs/fat/inode.c	2010-12-16 18:29:02.000000000 +1100
+++ linux-2.6/fs/fat/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -645,7 +645,7 @@ static int __fat_write_inode(struct inod
 	spin_unlock(&sbi->inode_hash_lock);
 	mark_buffer_dirty(bh);
 	err = 0;
-	if (wait)
+	if (1 /* XXX: fix fsync and use wait */)
 		err = sync_dirty_buffer(bh);
 	brelse(bh);
 	return err;
Index: linux-2.6/fs/jfs/inode.c
===================================================================
--- linux-2.6.orig/fs/jfs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/jfs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -123,7 +123,7 @@ int jfs_commit_inode(struct inode *inode
 
 int jfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
-	int wait = wbc->sync_mode == WB_SYNC_ALL;
+	int wait = 1; /* XXX fix fsync and use wbc->sync_mode == WB_SYNC_ALL; */
 
 	if (test_cflag(COMMIT_Nolink, inode))
 		return 0;
Index: linux-2.6/fs/minix/inode.c
===================================================================
--- linux-2.6.orig/fs/minix/inode.c	2010-12-16 18:29:02.000000000 +1100
+++ linux-2.6/fs/minix/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -576,7 +576,7 @@ static int minix_write_inode(struct inod
 		bh = V2_minix_update_inode(inode);
 	if (!bh)
 		return -EIO;
-	if (wbc->sync_mode == WB_SYNC_ALL && buffer_dirty(bh)) {
+	if (1 /* XXX: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */ && buffer_dirty(bh)) {
 		sync_dirty_buffer(bh);
 		if (buffer_req(bh) && !buffer_uptodate(bh)) {
 			printk("IO error syncing minix inode [%s:%08lx]\n",
Index: linux-2.6/fs/omfs/inode.c
===================================================================
--- linux-2.6.orig/fs/omfs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/omfs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -169,7 +169,7 @@ static int __omfs_write_inode(struct ino
 
 static int omfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
-	return __omfs_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
+	return __omfs_write_inode(inode, 1 /* XXX: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */);
 }
 
 int omfs_sync_inode(struct inode *inode)
Index: linux-2.6/fs/reiserfs/inode.c
===================================================================
--- linux-2.6.orig/fs/reiserfs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/reiserfs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -1635,6 +1635,8 @@ int reiserfs_write_inode(struct inode *i
 	 ** these cases are just when the system needs ram, not when the
 	 ** inode needs to reach disk for safety, and they can safely be
 	 ** ignored because the altered inode has already been logged.
+	 ** XXX: is this really OK? The caller clears the inode dirty bit, so
+	 ** a subsequent sync for integrity might never reach here.
 	 */
 	if (wbc->sync_mode == WB_SYNC_ALL && !(current->flags & PF_MEMALLOC)) {
 		reiserfs_write_lock(inode->i_sb);
Index: linux-2.6/fs/sysv/inode.c
===================================================================
--- linux-2.6.orig/fs/sysv/inode.c	2010-12-16 18:29:02.000000000 +1100
+++ linux-2.6/fs/sysv/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -286,7 +286,7 @@ static int __sysv_write_inode(struct ino
 		write3byte(sbi, (u8 *)&si->i_data[block],
 			&raw_inode->i_data[3*block]);
 	mark_buffer_dirty(bh);
-	if (wait) {
+	if (1 /* XXX: fix fsync and use wait */) {
                 sync_dirty_buffer(bh);
                 if (buffer_req(bh) && !buffer_uptodate(bh)) {
                         printk ("IO error syncing sysv inode [%s:%08x]\n",
Index: linux-2.6/fs/udf/inode.c
===================================================================
--- linux-2.6.orig/fs/udf/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/udf/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -1598,7 +1598,7 @@ static int udf_update_inode(struct inode
 
 	/* write the data blocks */
 	mark_buffer_dirty(bh);
-	if (do_sync) {
+	if (1 /* XXX fix fsync and use do_sync */) {
 		sync_dirty_buffer(bh);
 		if (buffer_write_io_error(bh)) {
 			printk(KERN_WARNING "IO error syncing udf inode "
Index: linux-2.6/fs/ufs/inode.c
===================================================================
--- linux-2.6.orig/fs/ufs/inode.c	2010-12-11 20:57:04.000000000 +1100
+++ linux-2.6/fs/ufs/inode.c	2010-12-16 18:33:25.000000000 +1100
@@ -889,7 +889,7 @@ static int ufs_update_inode(struct inode
 	}
 		
 	mark_buffer_dirty(bh);
-	if (do_sync)
+	if (1 /* XXX: fix fsync and use do_sync */)
 		sync_dirty_buffer(bh);
 	brelse (bh);
 	


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