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Commit 2813d682 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Ben Myers
Browse files

xfs: remove the i_new_size field in struct xfs_inode 



Now that we use the VFS i_size field throughout XFS there is no need for the
i_new_size field any more given that the VFS i_size field gets updated
in ->write_end before unlocking the page, and thus is always uptodate when
writeback could see a page.  Removing i_new_size also has the advantage that
we will never have to trim back di_size during a failed buffered write,
given that it never gets updated past i_size.

Note that currently the generic direct I/O code only updates i_size after
calling our end_io handler, which requires a small workaround to make
sure di_size actually makes it to disk.  I hope to fix this properly in
the generic code.

A downside is that we lose the support for parallel non-overlapping O_DIRECT
appending writes that recently was added.  I don't think keeping the complex
and fragile i_new_size infrastructure for this is a good tradeoff - if we
really care about parallel appending writers we should investigate turning
the iolock into a range lock, which would also allow for parallel
non-overlapping buffered writers.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent ce7ae151

fs/xfs/xfs_aops.c

+16 −13
Original line number Diff line number Diff line
@@ -111,8 +111,7 @@ xfs_ioend_new_eof( 
	xfs_fsize_t		bsize;



	bsize = ioend->io_offset + ioend->io_size;

	isize = MAX(i_size_read(VFS_I(ip)), ip->i_new_size);

	isize = MIN(isize, bsize);

	isize = MIN(i_size_read(VFS_I(ip)), bsize);

	return isize > ip->i_d.di_size ? isize : 0;

}
@@ -126,11 +125,7 @@ static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend) 
}



/*

 * Update on-disk file size now that data has been written to disk.  The

 * current in-memory file size is i_size.  If a write is beyond eof i_new_size

 * will be the intended file size until i_size is updated.  If this write does

 * not extend all the way to the valid file size then restrict this update to

 * the end of the write.

 * Update on-disk file size now that data has been written to disk.

 *

 * This function does not block as blocking on the inode lock in IO completion

 * can lead to IO completion order dependency deadlocks.. If it can't get the
@@ -1278,6 +1273,15 @@ xfs_end_io_direct_write( 
{

	struct xfs_ioend	*ioend = iocb->private;



	/*

	 * While the generic direct I/O code updates the inode size, it does

	 * so only after the end_io handler is called, which means our

	 * end_io handler thinks the on-disk size is outside the in-core

	 * size.  To prevent this just update it a little bit earlier here.

	 */

	if (offset + size > i_size_read(ioend->io_inode))

		i_size_write(ioend->io_inode, offset + size);



	/*

	 * blockdev_direct_IO can return an error even after the I/O

	 * completion handler was called.  Thus we need to protect
@@ -1340,12 +1344,11 @@ xfs_vm_write_failed( 


	if (to > inode->i_size) {

		/*

		 * punch out the delalloc blocks we have already allocated. We

		 * don't call xfs_setattr() to do this as we may be in the

		 * middle of a multi-iovec write and so the vfs inode->i_size

		 * will not match the xfs ip->i_size and so it will zero too

		 * much. Hence we jus truncate the page cache to zero what is

		 * necessary and punch the delalloc blocks directly.

		 * Punch out the delalloc blocks we have already allocated.

		 *

		 * Don't bother with xfs_setattr given that nothing can have

		 * made it to disk yet as the page is still locked at this

		 * point.

		 */

		struct xfs_inode	*ip = XFS_I(inode);

		xfs_fileoff_t		start_fsb;

fs/xfs/xfs_file.c

+10 −62
Original line number Diff line number Diff line
@@ -412,27 +412,6 @@ xfs_file_splice_read( 
	return ret;

}



/*

 * If this was a direct or synchronous I/O that failed (such as ENOSPC) then

 * part of the I/O may have been written to disk before the error occurred.  In

 * this case the on-disk file size may have been adjusted beyond the in-memory

 * file size and now needs to be truncated back.

 */

STATIC void

xfs_aio_write_newsize_update(

	struct xfs_inode	*ip,

	xfs_fsize_t		new_size)

{

	if (new_size == ip->i_new_size) {

		xfs_rw_ilock(ip, XFS_ILOCK_EXCL);

		if (new_size == ip->i_new_size)

			ip->i_new_size = 0;

		if (ip->i_d.di_size > i_size_read(VFS_I(ip)))

			ip->i_d.di_size = i_size_read(VFS_I(ip));

		xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);

	}

}



/*

 * xfs_file_splice_write() does not use xfs_rw_ilock() because

 * generic_file_splice_write() takes the i_mutex itself. This, in theory,
@@ -451,7 +430,6 @@ xfs_file_splice_write( 
{

	struct inode		*inode = outfilp->f_mapping->host;

	struct xfs_inode	*ip = XFS_I(inode);

	xfs_fsize_t		new_size;

	int			ioflags = 0;

	ssize_t			ret;
@@ -465,20 +443,12 @@ xfs_file_splice_write( 


	xfs_ilock(ip, XFS_IOLOCK_EXCL);



	new_size = *ppos + count;



	xfs_ilock(ip, XFS_ILOCK_EXCL);

	if (new_size > i_size_read(inode))

		ip->i_new_size = new_size;

	xfs_iunlock(ip, XFS_ILOCK_EXCL);



	trace_xfs_file_splice_write(ip, count, *ppos, ioflags);



	ret = generic_file_splice_write(pipe, outfilp, ppos, count, flags);

	if (ret > 0)

		XFS_STATS_ADD(xs_write_bytes, ret);



	xfs_aio_write_newsize_update(ip, new_size);

	xfs_iunlock(ip, XFS_IOLOCK_EXCL);

	return ret;

}
@@ -673,16 +643,13 @@ xfs_file_aio_write_checks( 
	struct file		*file,

	loff_t			*pos,

	size_t			*count,

	xfs_fsize_t		*new_sizep,

	int			*iolock)

{

	struct inode		*inode = file->f_mapping->host;

	struct xfs_inode	*ip = XFS_I(inode);

	xfs_fsize_t		new_size;

	int			error = 0;



	xfs_rw_ilock(ip, XFS_ILOCK_EXCL);

	*new_sizep = 0;

restart:

	error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));

	if (error) {
@@ -697,15 +664,13 @@ xfs_file_aio_write_checks( 
	/*

	 * If the offset is beyond the size of the file, we need to zero any

	 * blocks that fall between the existing EOF and the start of this

	 * write. There is no need to issue zeroing if another in-flght IO ends

	 * at or before this one If zeronig is needed and we are currently

	 * holding the iolock shared, we need to update it to exclusive which

	 * involves dropping all locks and relocking to maintain correct locking

	 * order. If we do this, restart the function to ensure all checks and

	 * values are still valid.

	 * write.  If zeroing is needed and we are currently holding the

	 * iolock shared, we need to update it to exclusive which involves

	 * dropping all locks and relocking to maintain correct locking order.

	 * If we do this, restart the function to ensure all checks and values

	 * are still valid.

	 */

	if ((ip->i_new_size && *pos > ip->i_new_size) ||

	    (!ip->i_new_size && *pos > i_size_read(inode))) {

	if (*pos > i_size_read(inode)) {

		if (*iolock == XFS_IOLOCK_SHARED) {

			xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);

			*iolock = XFS_IOLOCK_EXCL;
@@ -714,19 +679,6 @@ xfs_file_aio_write_checks( 
		}

		error = -xfs_zero_eof(ip, *pos, i_size_read(inode));

	}



	/*

	 * If this IO extends beyond EOF, we may need to update ip->i_new_size.

	 * We have already zeroed space beyond EOF (if necessary).  Only update

	 * ip->i_new_size if this IO ends beyond any other in-flight writes.

	 */

	new_size = *pos + *count;

	if (new_size > i_size_read(inode)) {

		if (new_size > ip->i_new_size)

			ip->i_new_size = new_size;

		*new_sizep = new_size;

	}



	xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);

	if (error)

		return error;
@@ -772,7 +724,6 @@ xfs_file_dio_aio_write( 
	unsigned long		nr_segs,

	loff_t			pos,

	size_t			ocount,

	xfs_fsize_t		*new_size,

	int			*iolock)

{

	struct file		*file = iocb->ki_filp;
@@ -817,7 +768,7 @@ xfs_file_dio_aio_write( 
		xfs_rw_ilock(ip, *iolock);

	}



	ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);

	ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);

	if (ret)

		return ret;
@@ -855,7 +806,6 @@ xfs_file_buffered_aio_write( 
	unsigned long		nr_segs,

	loff_t			pos,

	size_t			ocount,

	xfs_fsize_t		*new_size,

	int			*iolock)

{

	struct file		*file = iocb->ki_filp;
@@ -869,7 +819,7 @@ xfs_file_buffered_aio_write( 
	*iolock = XFS_IOLOCK_EXCL;

	xfs_rw_ilock(ip, *iolock);



	ret = xfs_file_aio_write_checks(file, &pos, &count, new_size, iolock);

	ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);

	if (ret)

		return ret;
@@ -909,7 +859,6 @@ xfs_file_aio_write( 
	ssize_t			ret;

	int			iolock;

	size_t			ocount = 0;

	xfs_fsize_t		new_size = 0;



	XFS_STATS_INC(xs_write_calls);
@@ -929,10 +878,10 @@ xfs_file_aio_write( 


	if (unlikely(file->f_flags & O_DIRECT))

		ret = xfs_file_dio_aio_write(iocb, iovp, nr_segs, pos,

						ocount, &new_size, &iolock);

						ocount, &iolock);

	else

		ret = xfs_file_buffered_aio_write(iocb, iovp, nr_segs, pos,

						ocount, &new_size, &iolock);

						ocount, &iolock);



	if (ret <= 0)

		goto out_unlock;
@@ -953,7 +902,6 @@ xfs_file_aio_write( 
	}



out_unlock:

	xfs_aio_write_newsize_update(ip, new_size);

	xfs_rw_iunlock(ip, iolock);

	return ret;

}

fs/xfs/xfs_iget.c

+0 −1
Original line number Diff line number Diff line
@@ -94,7 +94,6 @@ xfs_inode_alloc( 
	ip->i_update_core = 0;

	ip->i_delayed_blks = 0;

	memset(&ip->i_d, 0, sizeof(xfs_icdinode_t));

	ip->i_new_size = 0;



	return ip;

}

fs/xfs/xfs_inode.h

+0 −2
Original line number Diff line number Diff line
@@ -246,8 +246,6 @@ typedef struct xfs_inode { 


	xfs_icdinode_t		i_d;		/* most of ondisk inode */



	xfs_fsize_t		i_new_size;	/* size when write completes */



	/* VFS inode */

	struct inode		i_vnode;	/* embedded VFS inode */

} xfs_inode_t;

fs/xfs/xfs_trace.h

+4 −14
Original line number Diff line number Diff line
@@ -891,7 +891,6 @@ DECLARE_EVENT_CLASS(xfs_file_class, 
		__field(dev_t, dev)

		__field(xfs_ino_t, ino)

		__field(xfs_fsize_t, size)

		__field(xfs_fsize_t, new_size)

		__field(loff_t, offset)

		__field(size_t, count)

		__field(int, flags)
@@ -900,17 +899,15 @@ DECLARE_EVENT_CLASS(xfs_file_class, 
		__entry->dev = VFS_I(ip)->i_sb->s_dev;

		__entry->ino = ip->i_ino;

		__entry->size = ip->i_d.di_size;

		__entry->new_size = ip->i_new_size;

		__entry->offset = offset;

		__entry->count = count;

		__entry->flags = flags;

	),

	TP_printk("dev %d:%d ino 0x%llx size 0x%llx new_size 0x%llx "

	TP_printk("dev %d:%d ino 0x%llx size 0x%llx "

		  "offset 0x%llx count 0x%zx ioflags %s",

		  MAJOR(__entry->dev), MINOR(__entry->dev),

		  __entry->ino,

		  __entry->size,

		  __entry->new_size,

		  __entry->offset,

		  __entry->count,

		  __print_flags(__entry->flags, "|", XFS_IO_FLAGS))
@@ -978,7 +975,6 @@ DECLARE_EVENT_CLASS(xfs_imap_class, 
		__field(dev_t, dev)

		__field(xfs_ino_t, ino)

		__field(loff_t, size)

		__field(loff_t, new_size)

		__field(loff_t, offset)

		__field(size_t, count)

		__field(int, type)
@@ -990,7 +986,6 @@ DECLARE_EVENT_CLASS(xfs_imap_class, 
		__entry->dev = VFS_I(ip)->i_sb->s_dev;

		__entry->ino = ip->i_ino;

		__entry->size = ip->i_d.di_size;

		__entry->new_size = ip->i_new_size;

		__entry->offset = offset;

		__entry->count = count;

		__entry->type = type;
@@ -998,13 +993,11 @@ DECLARE_EVENT_CLASS(xfs_imap_class, 
		__entry->startblock = irec ? irec->br_startblock : 0;

		__entry->blockcount = irec ? irec->br_blockcount : 0;

	),

	TP_printk("dev %d:%d ino 0x%llx size 0x%llx new_size 0x%llx "

		  "offset 0x%llx count %zd type %s "

		  "startoff 0x%llx startblock %lld blockcount 0x%llx",

	TP_printk("dev %d:%d ino 0x%llx size 0x%llx offset 0x%llx count %zd "

		  "type %s startoff 0x%llx startblock %lld blockcount 0x%llx",

		  MAJOR(__entry->dev), MINOR(__entry->dev),

		  __entry->ino,

		  __entry->size,

		  __entry->new_size,

		  __entry->offset,

		  __entry->count,

		  __print_symbolic(__entry->type, XFS_IO_TYPES),
@@ -1031,7 +1024,6 @@ DECLARE_EVENT_CLASS(xfs_simple_io_class, 
		__field(xfs_ino_t, ino)

		__field(loff_t, isize)

		__field(loff_t, disize)

		__field(loff_t, new_size)

		__field(loff_t, offset)

		__field(size_t, count)

	),
@@ -1040,17 +1032,15 @@ DECLARE_EVENT_CLASS(xfs_simple_io_class, 
		__entry->ino = ip->i_ino;

		__entry->isize = VFS_I(ip)->i_size;

		__entry->disize = ip->i_d.di_size;

		__entry->new_size = ip->i_new_size;

		__entry->offset = offset;

		__entry->count = count;

	),

	TP_printk("dev %d:%d ino 0x%llx isize 0x%llx disize 0x%llx new_size 0x%llx "

	TP_printk("dev %d:%d ino 0x%llx isize 0x%llx disize 0x%llx "

		  "offset 0x%llx count %zd",

		  MAJOR(__entry->dev), MINOR(__entry->dev),

		  __entry->ino,

		  __entry->isize,

		  __entry->disize,

		  __entry->new_size,

		  __entry->offset,

		  __entry->count)

);