[PATCH] add -o flush for fat

[Chris Mason <mason@suse.com>]

From: Chris Mason <mason@suse.com>
Subject: add -o flush for fat

Fat is commonly used on removable media, mounting with -o flush tells the
FS to write things to disk as quickly as possible.  It is like -o sync, but
much faster (and not as safe).

Signed-off-by: Chris Mason <mason@suse.com>

--- a/fs/fat/file.c	Fri Aug 04 14:02:26 2006 -0400
+++ b/fs/fat/file.c	Fri Aug 04 15:25:09 2006 -0400
@@ -13,6 +13,7 @@
 #include <linux/smp_lock.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
+#include <linux/blkdev.h>
 
 int fat_generic_ioctl(struct inode *inode, struct file *filp,
 		      unsigned int cmd, unsigned long arg)
@@ -112,6 +113,17 @@ int fat_generic_ioctl(struct inode *inod
 	}
 }
 
+static int fat_file_release(struct inode *inode, struct file *filp)
+{
+	if ((filp->f_mode & FMODE_WRITE) &&
+	     MSDOS_SB(inode->i_sb)->options.flush) {
+		writeback_inode(inode);
+		writeback_bdev(inode->i_sb);
+		blk_congestion_wait(WRITE, HZ/10);
+	}
+	return 0;
+}
+
 const struct file_operations fat_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= do_sync_read,
@@ -121,6 +133,7 @@ const struct file_operations fat_file_op
 	.aio_read	= generic_file_aio_read,
 	.aio_write	= generic_file_aio_write,
 	.mmap		= generic_file_mmap,
+	.release	= fat_file_release,
 	.ioctl		= fat_generic_ioctl,
 	.fsync		= file_fsync,
 	.sendfile	= generic_file_sendfile,
@@ -289,6 +302,10 @@ void fat_truncate(struct inode *inode)
 	lock_kernel();
 	fat_free(inode, nr_clusters);
 	unlock_kernel();
+	if (MSDOS_SB(inode->i_sb)->options.flush) {
+		writeback_inode(inode);
+		writeback_bdev(inode->i_sb);
+	}
 }
 
 struct inode_operations fat_file_inode_operations = {
--- a/fs/fat/inode.c	Fri Aug 04 14:02:26 2006 -0400
+++ b/fs/fat/inode.c	Fri Aug 04 14:02:26 2006 -0400
@@ -24,6 +24,7 @@
 #include <linux/vfs.h>
 #include <linux/parser.h>
 #include <linux/uio.h>
+#include <linux/writeback.h>
 #include <asm/unaligned.h>
 
 #ifndef CONFIG_FAT_DEFAULT_IOCHARSET
@@ -861,7 +862,7 @@ enum {
 	Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
 	Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
 	Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
-	Opt_obsolate, Opt_err,
+	Opt_obsolate, Opt_flush, Opt_err,
 };
 
 static match_table_t fat_tokens = {
@@ -893,7 +894,8 @@ static match_table_t fat_tokens = {
 	{Opt_obsolate, "cvf_format=%20s"},
 	{Opt_obsolate, "cvf_options=%100s"},
 	{Opt_obsolate, "posix"},
-	{Opt_err, NULL}
+	{Opt_flush, "flush"},
+	{Opt_err, NULL},
 };
 static match_table_t msdos_tokens = {
 	{Opt_nodots, "nodots"},
@@ -1034,6 +1036,9 @@ static int parse_options(char *options, 
 				return 0;
 			opts->codepage = option;
 			break;
+		case Opt_flush:
+			opts->flush = 1;
+			break;
 
 		/* msdos specific */
 		case Opt_dots:
--- a/fs/fs-writeback.c	Fri Aug 04 14:02:26 2006 -0400
+++ b/fs/fs-writeback.c	Fri Aug 04 14:41:46 2006 -0400
@@ -391,6 +391,41 @@ sync_sb_inodes(struct super_block *sb, s
 }
 
 /*
+ * starts IO on any dirty blocks in the block device.  This uses
+ * filemap_flush, and so it does not wait for the io to finish, and does
+ * not wait on any IO currently in flight.
+ */
+void writeback_bdev(struct super_block *sb)
+{
+	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
+	filemap_flush(mapping);
+}
+EXPORT_SYMBOL_GPL(writeback_bdev);
+
+/*
+ * start writeback on both the inode and the data blocks.
+ * filemap_fdatawrite is used, so it waits for any IO that was in
+ * flight for dirty blocks at the start of this call.  This will not
+ * wait for any IO it starts.
+ */
+void writeback_inode(struct inode *inode)
+{
+
+	struct address_space *mapping = inode->i_mapping;
+	struct writeback_control wbc = {
+		.sync_mode = WB_SYNC_NONE,
+		.nr_to_write = 0,
+	};
+	/* if we used WB_SYNC_ALL, sync_inode waits for the io for the
+	 * inode to finish.  So WB_SYNC_NONE is sent down to sync_inode
+	 * and filemap_fdatawrite is used for the data blocks
+	 */
+	sync_inode(inode, &wbc);
+	filemap_fdatawrite(mapping);
+}
+EXPORT_SYMBOL_GPL(writeback_inode);
+
+/*
  * Start writeback of dirty pagecache data against all unlocked inodes.
  *
  * Note:
--- a/fs/msdos/namei.c	Fri Aug 04 14:02:26 2006 -0400
+++ b/fs/msdos/namei.c	Fri Aug 04 14:02:26 2006 -0400
@@ -11,6 +11,7 @@
 #include <linux/buffer_head.h>
 #include <linux/msdos_fs.h>
 #include <linux/smp_lock.h>
+#include <linux/writeback.h>
 
 /* Characters that are undesirable in an MS-DOS file name */
 static unsigned char bad_chars[] = "*?<>|\"";
@@ -280,7 +281,7 @@ static int msdos_create(struct inode *di
 			struct nameidata *nd)
 {
 	struct super_block *sb = dir->i_sb;
-	struct inode *inode;
+	struct inode *inode = NULL;
 	struct fat_slot_info sinfo;
 	struct timespec ts;
 	unsigned char msdos_name[MSDOS_NAME];
@@ -316,6 +317,11 @@ static int msdos_create(struct inode *di
 	d_instantiate(dentry, inode);
 out:
 	unlock_kernel();
+	if (!err && MSDOS_SB(sb)->options.flush) {
+		writeback_inode(dir);
+		writeback_inode(inode);
+		writeback_bdev(sb);
+	}
 	return err;
 }
 
@@ -348,6 +354,11 @@ static int msdos_rmdir(struct inode *dir
 	fat_detach(inode);
 out:
 	unlock_kernel();
+	if (!err && MSDOS_SB(inode->i_sb)->options.flush) {
+		writeback_inode(dir);
+		writeback_inode(inode);
+		writeback_bdev(inode->i_sb);
+	}
 
 	return err;
 }
@@ -401,6 +412,11 @@ static int msdos_mkdir(struct inode *dir
 	d_instantiate(dentry, inode);
 
 	unlock_kernel();
+	if (MSDOS_SB(sb)->options.flush) {
+		writeback_inode(dir);
+		writeback_inode(inode);
+		writeback_bdev(sb);
+	}
 	return 0;
 
 out_free:
@@ -430,6 +446,11 @@ static int msdos_unlink(struct inode *di
 	fat_detach(inode);
 out:
 	unlock_kernel();
+	if (!err && MSDOS_SB(inode->i_sb)->options.flush) {
+		writeback_inode(dir);
+		writeback_inode(inode);
+		writeback_bdev(inode->i_sb);
+	}
 
 	return err;
 }
@@ -635,6 +656,11 @@ static int msdos_rename(struct inode *ol
 			      new_dir, new_msdos_name, new_dentry, is_hid);
 out:
 	unlock_kernel();
+	if (!err && MSDOS_SB(old_dir->i_sb)->options.flush) {
+		writeback_inode(old_dir);
+		writeback_inode(new_dir);
+		writeback_bdev(old_dir->i_sb);
+	}
 	return err;
 }
 
--- a/include/linux/msdos_fs.h	Fri Aug 04 14:02:26 2006 -0400
+++ b/include/linux/msdos_fs.h	Fri Aug 04 14:02:26 2006 -0400
@@ -204,6 +204,7 @@ struct fat_mount_options {
 		 unicode_xlate:1, /* create escape sequences for unhandled Unicode */
 		 numtail:1,       /* Does first alias have a numeric '~1' type tail? */
 		 atari:1,         /* Use Atari GEMDOS variation of MS-DOS fs */
+		 flush:1,	  /* write things quickly */
 		 nocase:1;	  /* Does this need case conversion? 0=need case conversion*/
 };
 
--- a/include/linux/writeback.h	Fri Aug 04 14:02:26 2006 -0400
+++ b/include/linux/writeback.h	Fri Aug 04 14:02:26 2006 -0400
@@ -69,6 +69,8 @@ int inode_wait(void *);
 int inode_wait(void *);
 void sync_inodes_sb(struct super_block *, int wait);
 void sync_inodes(int wait);
+void writeback_bdev(struct super_block *);
+void writeback_inode(struct inode *);
 
 /* writeback.h requires fs.h; it, too, is not included from here. */
 static inline void wait_on_inode(struct inode *inode)