Re: [PATCH 1/2][FAT] miss-sync issues on sync mount (miss-sync on write)

From: OGAWA Hirofumi (hirofumi_at_mail.parknet.co.jp)
Date: 09/15/05

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    To: Andrew Morton <akpm@osdl.org>
Date:	Thu, 15 Sep 2005 21:43:12 +0900

    Andrew Morton <akpm@osdl.org> writes:

    > "Machida, Hiroyuki" <machida@sm.sony.co.jp> wrote:
    >>
    >> This patch fixes miss-sync issue on write() system call.
    >> This updates inode attrs flags, mtime and ctime on every
    >> comit_write call, due to locking.
    >
    > This all seems wrong.
    >
    > Why does fatfs have file_operations.write pointing at do_sync_write()
    > rather than generic_file_write()?
    >
    > Why does fatfs have a custom .aio_write() rather than using
    > generic_file_aio_write()?
    >
    > If fatfs can use all the standard library functions, all this inode
    > dirtying and O_SYNC/-o sync handling shoud just work.

    In fat_file_aio_write:

            retval = generic_file_aio_write(iocb, buf, count, pos);
            if (retval > 0) {
                    inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
                    MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
                    mark_inode_dirty(inode);

    He says about the above FAT specific flag and timestamp. FAT needs to
    add the ATTR_ARCH if data was modified, but current FAT is adding it
    after generic_file_aio_write()/generic_file_writev(). (IIRC, some
    other filesystems is also doing this.)

    His patch seems good, although the some additional works was needed.
    I applied the attached patch. Thanks, Hiroyuki-san.

    Andrew, now fat_file_operations is the following. Is this OK?

    struct file_operations fat_file_operations = {
            .llseek = generic_file_llseek,
            .read = do_sync_read,
            .write = do_sync_write,
            .readv = generic_file_readv,
            .writev = generic_file_writev,
            .aio_read = generic_file_aio_read,
            .aio_write = generic_file_aio_write,
            .mmap = generic_file_mmap,
            .ioctl = fat_generic_ioctl,
            .fsync = file_fsync,
            .sendfile = generic_file_sendfile,
    }; 

    -- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
[PATCH] FAT: miss-sync issues on sync mount (miss-sync on write)
This patch fixes miss-sync issue on write() system call.
This updates inode attrs flags, mtime and ctime on every
comit_write call, due to locking.
Signed-off-by: Hiroyuki Machida <machida@sm.sony.co.jp>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
 fs/fat/file.c  |   37 ++-----------------------------------
 fs/fat/inode.c |   15 ++++++++++++++-
 2 files changed, 16 insertions(+), 36 deletions(-)
diff -puN fs/fat/file.c~fat_arch-flags-fix fs/fat/file.c
--- linux-2.6.14-rc1/fs/fat/file.c~fat_arch-flags-fix	2005-09-15 20:52:21.000000000 +0900
+++ linux-2.6.14-rc1-hirofumi/fs/fat/file.c	2005-09-15 20:55:12.000000000 +0900
@@ -12,39 +12,6 @@
 #include <linux/smp_lock.h>
 #include <linux/buffer_head.h>
 
-static ssize_t fat_file_aio_write(struct kiocb *iocb, const char __user *buf,
-				  size_t count, loff_t pos)
-{
-	struct inode *inode = iocb->ki_filp->f_dentry->d_inode;
-	int retval;
-
-	retval = generic_file_aio_write(iocb, buf, count, pos);
-	if (retval > 0) {
-		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
-		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
-		mark_inode_dirty(inode);
-//		check the locking rules
-//		if (IS_SYNC(inode))
-//			fat_sync_inode(inode);
-	}
-	return retval;
-}
-
-static ssize_t fat_file_writev(struct file *filp, const struct iovec *iov,
-			       unsigned long nr_segs, loff_t *ppos)
-{
-	struct inode *inode = filp->f_dentry->d_inode;
-	int retval;
-
-	retval = generic_file_writev(filp, iov, nr_segs, ppos);
-	if (retval > 0) {
-		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
-		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
-		mark_inode_dirty(inode);
-	}
-	return retval;
-}
-
 int fat_generic_ioctl(struct inode *inode, struct file *filp,
 		      unsigned int cmd, unsigned long arg)
 {
@@ -148,9 +115,9 @@ struct file_operations fat_file_operatio
 	.read		= do_sync_read,
 	.write		= do_sync_write,
 	.readv		= generic_file_readv,
-	.writev		= fat_file_writev,
+	.writev		= generic_file_writev,
 	.aio_read	= generic_file_aio_read,
-	.aio_write	= fat_file_aio_write,
+	.aio_write	= generic_file_aio_write,
 	.mmap		= generic_file_mmap,
 	.ioctl		= fat_generic_ioctl,
 	.fsync		= file_fsync,
diff -puN fs/fat/inode.c~fat_arch-flags-fix fs/fat/inode.c
--- linux-2.6.14-rc1/fs/fat/inode.c~fat_arch-flags-fix	2005-09-15 20:52:21.000000000 +0900
+++ linux-2.6.14-rc1-hirofumi/fs/fat/inode.c	2005-09-15 21:32:51.000000000 +0900
@@ -102,6 +102,19 @@ static int fat_prepare_write(struct file
 				  &MSDOS_I(page->mapping->host)->mmu_private);
 }
 
+static int fat_commit_write(struct file *file, struct page *page,
+			    unsigned from, unsigned to)
+{
+	struct inode *inode = page->mapping->host;
+	int err = generic_commit_write(file, page, from, to);
+	if (!err && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
+		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
+		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
+		mark_inode_dirty(inode);
+	}
+	return err;
+}
+
 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 {
 	return generic_block_bmap(mapping, block, fat_get_block);
@@ -112,7 +125,7 @@ static struct address_space_operations f
 	.writepage	= fat_writepage,
 	.sync_page	= block_sync_page,
 	.prepare_write	= fat_prepare_write,
-	.commit_write	= generic_commit_write,
+	.commit_write	= fat_commit_write,
 	.bmap		= _fat_bmap
 };
 
_
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