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ctime/mtime update in affs and hpfs write path

PATCH In review Christoph Hellwig 3 participants 5 messages Oct 31, 2005 – Nov 3, 2005

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VFS Affs file system
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Christoph Hellwig

author
#0 lore raw

Both AFFS and HPFS update the ctime and mtime in the write path, after generic_file_write returned and mark the inode dirty. Anyone's got an idea why these two filesystems aren't happy with the ctime/mtime updates vi generic_file_write before we copied the data into the pagecache?

#1 lore raw

Hi,

Quoted 4 lines · Christoph Hellwig

Both AFFS and HPFS update the ctime and mtime in the write path, after generic_file_write returned and mark the inode dirty. Anyone's got an idea why these two filesystems aren't happy with the ctime/mtime updates vi generic_file_write before we copied the data into the pagecache?

For affs I don't really know, my best guess is it has been there forever and there never was a reason to remove it.

bye, Roman

author
#2 lore raw

PATCH 1/1 remove superflous ctime/mtime updates in affs

Quoted 7 lines · Roman Zippel
Quoted 4 lines

Both AFFS and HPFS update the ctime and mtime in the write path, after generic_file_write returned and mark the inode dirty. Anyone's got an idea why these two filesystems aren't happy with the ctime/mtime updates vi generic_file_write before we copied the data into the pagecache?

For affs I don't really know, my best guess is it has been there forever and there never was a reason to remove it.

Ok, what about the following patch?

Signed-off-by Christoph Hellwig <[email protected]>
fs/affs/file.c +1 -17
Index: linux-2.6/fs/affs/file.c
===================================================================
@@ -22,14 +22,13 @@
 static struct buffer_head *affs_alloc_extblock(struct inode *inode, struct buffer_head *bh, u32 ext);
 static inline struct buffer_head *affs_get_extblock(struct inode *inode, u32 ext);
 static struct buffer_head *affs_get_extblock_slow(struct inode *inode, u32 ext);
-static ssize_t affs_file_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos);
 static int affs_file_open(struct inode *inode, struct file *filp);
 static int affs_file_release(struct inode *inode, struct file *filp);
 
 struct file_operations affs_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= generic_file_read,
-	.write		= affs_file_write,
+	.write		= generic_file_write,
 	.mmap		= generic_file_mmap,
 	.open		= affs_file_open,
 	.release	= affs_file_release,

@@ -473,21 +472,6 @@
 	return ERR_PTR(err);
 }
 
-static ssize_t
-affs_file_write(struct file *file, const char __user *buf,
-		size_t count, loff_t *ppos)
-{
-	ssize_t retval;
-
-	retval = generic_file_write (file, buf, count, ppos);
-	if (retval >0) {
-		struct inode *inode = file->f_dentry->d_inode;
-		inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
-		mark_inode_dirty(inode);
-	}
-	return retval;
-}
-
 static int
 affs_do_readpage_ofs(struct file *file, struct page *page, unsigned from, unsigned to)
 {
#4 lore raw
In reply to Christoph Hellwig
Quoted 4 lines · Christoph Hellwig

Both AFFS and HPFS update the ctime and mtime in the write path, after generic_file_write returned and mark the inode dirty. Anyone's got an idea why these two filesystems aren't happy with the ctime/mtime updates vi generic_file_write before we copied the data into the pagecache?

In HPFS, there's no reason for mtime update --- just that it was left when porting code from older kernels. If generic_file_write updates it, you can remove update in HPFS.

As for inode dirty --- HPFS has its own dirty mechanism different from the kernel to avoid deadlocks (writing inode on HPFS needs to lock parent directory and you can't do it from ->write_inode method) --- let it be, it may be slower, but it's stable.

Mikulas