Ping? Omar confirms it fixes xfs for him, so all this needs now is a
formal review...
--D
On Wed, Dec 04, 2019 at 08:38:09AM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Omar Sandoval reported that a 4G fallocate on the realtime device causes
> filesystem shutdowns due to a log reservation overflow that happens when
> we log the rtbitmap updates. Factor rtbitmap/rtsummary updates into the
> the tr_write and tr_itruncate log reservation calculation.
>
> "The following reproducer results in a transaction log overrun warning
> for me:
>
> mkfs.xfs -f -r rtdev=/dev/vdc -d rtinherit=1 -m reflink=0 /dev/vdb
> mount -o rtdev=/dev/vdc /dev/vdb /mnt
> fallocate -l 4G /mnt/foo
>
> Reported-by: Omar Sandoval <osandov@xxxxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_trans_resv.c | 96 ++++++++++++++++++++++++++++++++--------
> 1 file changed, 77 insertions(+), 19 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c
> index c55cd9a3dec9..824073a839ac 100644
> --- a/fs/xfs/libxfs/xfs_trans_resv.c
> +++ b/fs/xfs/libxfs/xfs_trans_resv.c
> @@ -196,6 +196,24 @@ xfs_calc_inode_chunk_res(
> return res;
> }
>
> +/*
> + * Per-extent log reservation for the btree changes involved in freeing or
> + * allocating a realtime extent. We have to be able to log as many rtbitmap
> + * blocks as needed to mark inuse MAXEXTLEN blocks' worth of realtime extents,
> + * as well as the realtime summary block.
> + */
> +unsigned int
> +xfs_rtalloc_log_count(
> + struct xfs_mount *mp,
> + unsigned int num_ops)
> +{
> + unsigned int blksz = XFS_FSB_TO_B(mp, 1);
> + unsigned int rtbmp_bytes;
> +
> + rtbmp_bytes = (MAXEXTLEN / mp->m_sb.sb_rextsize) / NBBY;
> + return (howmany(rtbmp_bytes, blksz) + 1) * num_ops;
> +}
> +
> /*
> * Various log reservation values.
> *
> @@ -218,13 +236,21 @@ xfs_calc_inode_chunk_res(
>
> /*
> * In a write transaction we can allocate a maximum of 2
> - * extents. This gives:
> + * extents. This gives (t1):
> * the inode getting the new extents: inode size
> * the inode's bmap btree: max depth * block size
> * the agfs of the ags from which the extents are allocated: 2 * sector
> * the superblock free block counter: sector size
> * the allocation btrees: 2 exts * 2 trees * (2 * max depth - 1) * block size
> - * And the bmap_finish transaction can free bmap blocks in a join:
> + * Or, if we're writing to a realtime file (t2):
> + * the inode getting the new extents: inode size
> + * the inode's bmap btree: max depth * block size
> + * the agfs of the ags from which the extents are allocated: 2 * sector
> + * the superblock free block counter: sector size
> + * the realtime bitmap: ((MAXEXTLEN / rtextsize) / NBBY) bytes
> + * the realtime summary: 1 block
> + * the allocation btrees: 2 trees * (2 * max depth - 1) * block size
> + * And the bmap_finish transaction can free bmap blocks in a join (t3):
> * the agfs of the ags containing the blocks: 2 * sector size
> * the agfls of the ags containing the blocks: 2 * sector size
> * the super block free block counter: sector size
> @@ -234,40 +260,72 @@ STATIC uint
> xfs_calc_write_reservation(
> struct xfs_mount *mp)
> {
> - return XFS_DQUOT_LOGRES(mp) +
> - max((xfs_calc_inode_res(mp, 1) +
> + unsigned int t1, t2, t3;
> + unsigned int blksz = XFS_FSB_TO_B(mp, 1);
> +
> + t1 = xfs_calc_inode_res(mp, 1) +
> + xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK), blksz) +
> + xfs_calc_buf_res(3, mp->m_sb.sb_sectsize) +
> + xfs_calc_buf_res(xfs_allocfree_log_count(mp, 2), blksz);
> +
> + if (xfs_sb_version_hasrealtime(&mp->m_sb)) {
> + t2 = xfs_calc_inode_res(mp, 1) +
> xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK),
> - XFS_FSB_TO_B(mp, 1)) +
> + blksz) +
> xfs_calc_buf_res(3, mp->m_sb.sb_sectsize) +
> - xfs_calc_buf_res(xfs_allocfree_log_count(mp, 2),
> - XFS_FSB_TO_B(mp, 1))),
> - (xfs_calc_buf_res(5, mp->m_sb.sb_sectsize) +
> - xfs_calc_buf_res(xfs_allocfree_log_count(mp, 2),
> - XFS_FSB_TO_B(mp, 1))));
> + xfs_calc_buf_res(xfs_rtalloc_log_count(mp, 1), blksz) +
> + xfs_calc_buf_res(xfs_allocfree_log_count(mp, 1), blksz);
> + } else {
> + t2 = 0;
> + }
> +
> + t3 = xfs_calc_buf_res(5, mp->m_sb.sb_sectsize) +
> + xfs_calc_buf_res(xfs_allocfree_log_count(mp, 2), blksz);
> +
> + return XFS_DQUOT_LOGRES(mp) + max3(t1, t2, t3);
> }
>
> /*
> - * In truncating a file we free up to two extents at once. We can modify:
> + * In truncating a file we free up to two extents at once. We can modify (t1):
> * the inode being truncated: inode size
> * the inode's bmap btree: (max depth + 1) * block size
> - * And the bmap_finish transaction can free the blocks and bmap blocks:
> + * And the bmap_finish transaction can free the blocks and bmap blocks (t2):
> * the agf for each of the ags: 4 * sector size
> * the agfl for each of the ags: 4 * sector size
> * the super block to reflect the freed blocks: sector size
> * worst case split in allocation btrees per extent assuming 4 extents:
> * 4 exts * 2 trees * (2 * max depth - 1) * block size
> + * Or, if it's a realtime file (t3):
> + * the agf for each of the ags: 2 * sector size
> + * the agfl for each of the ags: 2 * sector size
> + * the super block to reflect the freed blocks: sector size
> + * the realtime bitmap: 2 exts * ((MAXEXTLEN / rtextsize) / NBBY) bytes
> + * the realtime summary: 2 exts * 1 block
> + * worst case split in allocation btrees per extent assuming 2 extents:
> + * 2 exts * 2 trees * (2 * max depth - 1) * block size
> */
> STATIC uint
> xfs_calc_itruncate_reservation(
> struct xfs_mount *mp)
> {
> - return XFS_DQUOT_LOGRES(mp) +
> - max((xfs_calc_inode_res(mp, 1) +
> - xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) + 1,
> - XFS_FSB_TO_B(mp, 1))),
> - (xfs_calc_buf_res(9, mp->m_sb.sb_sectsize) +
> - xfs_calc_buf_res(xfs_allocfree_log_count(mp, 4),
> - XFS_FSB_TO_B(mp, 1))));
> + unsigned int t1, t2, t3;
> + unsigned int blksz = XFS_FSB_TO_B(mp, 1);
> +
> + t1 = xfs_calc_inode_res(mp, 1) +
> + xfs_calc_buf_res(XFS_BM_MAXLEVELS(mp, XFS_DATA_FORK) + 1, blksz);
> +
> + t2 = xfs_calc_buf_res(9, mp->m_sb.sb_sectsize) +
> + xfs_calc_buf_res(xfs_allocfree_log_count(mp, 4), blksz);
> +
> + if (xfs_sb_version_hasrealtime(&mp->m_sb)) {
> + t3 = xfs_calc_buf_res(5, mp->m_sb.sb_sectsize) +
> + xfs_calc_buf_res(xfs_rtalloc_log_count(mp, 2), blksz) +
> + xfs_calc_buf_res(xfs_allocfree_log_count(mp, 2), blksz);
> + } else {
> + t3 = 0;
> + }
> +
> + return XFS_DQUOT_LOGRES(mp) + max3(t1, t2, t3);
> }
>
> /*
