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Commit 77e9ce32 authored by Al Viro's avatar Al Viro
Browse files

ufs: fix the logics for tail relocation 



* original hysteresis loop got broken by typo back in 2002; now
it never switches out of OPTTIME state.  Fixed.
* critical levels for switching from OPTTIME to OPTSPACE and back
ought to be calculated once, at mount time.
* we should use mul_u64_u32_div() for those calculations, now that
->s_dsize is 64bit.
* to quote Kirk McKusick (in 1995 FreeBSD commit message):
    The threshold for switching from time-space and space-time is too small
    when minfree is 5%...so make it stay at space in this case.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c0ef65d2

fs/ufs/balloc.c

+6 −16
Original line number Diff line number Diff line
@@ -455,24 +455,14 @@ u64 ufs_new_fragments(struct inode *inode, void *p, u64 fragment, 
	/*

	 * allocate new block and move data

	 */

	switch (fs32_to_cpu(sb, usb1->fs_optim)) {

	    case UFS_OPTSPACE:

	if (fs32_to_cpu(sb, usb1->fs_optim) == UFS_OPTSPACE) {

		request = newcount;

		if (uspi->s_minfree < 5 || uspi->cs_total.cs_nffree

		    > uspi->s_dsize * uspi->s_minfree / (2 * 100))

			break;

		usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);

		break;

	    default:

		if (uspi->cs_total.cs_nffree < uspi->s_space_to_time)

			usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);

	

	    case UFS_OPTTIME:

	} else {

		request = uspi->s_fpb;

		if (uspi->cs_total.cs_nffree < uspi->s_dsize *

		    (uspi->s_minfree - 2) / 100)

			break;

		usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTTIME);

		break;

		if (uspi->cs_total.cs_nffree > uspi->s_time_to_space)

			usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTSPACE);

	}

	result = ufs_alloc_fragments (inode, cgno, goal, request, err);

	if (result) {

fs/ufs/super.c

+9 −0
Original line number Diff line number Diff line
@@ -1211,6 +1211,15 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent) 


	uspi->s_root_blocks = mul_u64_u32_div(uspi->s_dsize,

					      uspi->s_minfree, 100);

	if (uspi->s_minfree <= 5) {

		uspi->s_time_to_space = ~0ULL;

		uspi->s_space_to_time = 0;

		usb1->fs_optim = cpu_to_fs32(sb, UFS_OPTSPACE);

	} else {

		uspi->s_time_to_space = (uspi->s_root_blocks / 2) + 1;

		uspi->s_space_to_time = mul_u64_u32_div(uspi->s_dsize,

					      uspi->s_minfree - 2, 100) - 1;

	}



	/*

	 * Compute another frequently used values

fs/ufs/ufs_fs.h

+2 −0
Original line number Diff line number Diff line
@@ -792,6 +792,8 @@ struct ufs_sb_private_info { 
	__s32	fs_magic;       /* filesystem magic */

	unsigned int s_dirblksize;

	__u64   s_root_blocks;

	__u64	s_time_to_space;

	__u64	s_space_to_time;

};



/*