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Commit 467f7899 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Ben Myers
Browse files

xfs: reduce ilock hold times in xfs_file_aio_write_checks 



We do not need the ilock for generic_write_checks and the i_size_read,
which are protected by i_mutex and/or iolock, so reduce the ilock
critical section to just the call to xfs_zero_eof.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarMark Tinguely <tinguely@sgi.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent b4d05e30

fs/xfs/xfs_file.c

+9 −14
Original line number Diff line number Diff line
@@ -593,35 +593,31 @@ xfs_file_aio_write_checks( 
	struct xfs_inode	*ip = XFS_I(inode);

	int			error = 0;



	xfs_rw_ilock(ip, XFS_ILOCK_EXCL);

restart:

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

	if (error) {

		xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);

	if (error)

		return error;

	}



	/*

	 * 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.  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.

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

	 * having to redo all checks before.

	 */

	if (*pos > i_size_read(inode)) {

		if (*iolock == XFS_IOLOCK_SHARED) {

			xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);

			xfs_rw_iunlock(ip, *iolock);

			*iolock = XFS_IOLOCK_EXCL;

			xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);

			xfs_rw_ilock(ip, *iolock);

			goto restart;

		}

		xfs_rw_ilock(ip, XFS_ILOCK_EXCL);

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

	}

		xfs_rw_iunlock(ip, XFS_ILOCK_EXCL);

		if (error)

			return error;

	}



	/*

	 * Updating the timestamps will grab the ilock again from
@@ -638,7 +634,6 @@ xfs_file_aio_write_checks( 
	 * people from modifying setuid and setgid binaries.

	 */

	return file_remove_suid(file);



}



/*