On 9/26/20 8:14 AM, xiakaixu1987@xxxxxxxxx wrote:
> From: Kaixu Xia <kaixuxia@xxxxxxxxxxx>
>
> Nowadays the only things that the XFS_TRANS_DQ_DIRTY flag seems to do
> are indicates the tp->t_dqinfo->dqs[XFS_QM_TRANS_{USR,GRP,PRJ}] values
> changed and check in xfs_trans_apply_dquot_deltas() and the unreserve
> variant xfs_trans_unreserve_and_mod_dquots(). Actually, we also can
> use the tp->t_dqinfo value instead of the XFS_TRANS_DQ_DIRTY flag, that
> is to say, we allocate the new tp->t_dqinfo only when the qtrx values
> changed, so the tp->t_dqinfo value isn't NULL equals the XFS_TRANS_DQ_DIRTY
> flag is set, we only need to check if tp->t_dqinfo == NULL in
> xfs_trans_apply_dquot_deltas() and its unreserve variant to determine
> whether lock all of the dquots and join them to the transaction.
>
> Signed-off-by: Kaixu Xia <kaixuxia@xxxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_shared.h | 1 -
> fs/xfs/xfs_inode.c | 8 +-------
> fs/xfs/xfs_trans_dquot.c | 20 ++------------------
> 3 files changed, 3 insertions(+), 26 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
> index c795ae47b3c9..8c61a461bf7b 100644
> --- a/fs/xfs/libxfs/xfs_shared.h
> +++ b/fs/xfs/libxfs/xfs_shared.h
> @@ -62,7 +62,6 @@ void xfs_log_get_max_trans_res(struct xfs_mount *mp,
> #define XFS_TRANS_SB_DIRTY 0x02 /* superblock is modified */
> #define XFS_TRANS_PERM_LOG_RES 0x04 /* xact took a permanent log res */
> #define XFS_TRANS_SYNC 0x08 /* make commit synchronous */
> -#define XFS_TRANS_DQ_DIRTY 0x10 /* at least one dquot in trx dirty */
> #define XFS_TRANS_RESERVE 0x20 /* OK to use reserved data blocks */
> #define XFS_TRANS_NO_WRITECOUNT 0x40 /* do not elevate SB writecount */
> #define XFS_TRANS_RES_FDBLKS 0x80 /* reserve newly freed blocks */
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 49624973eecc..9108eed0ea45 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -941,7 +941,6 @@ xfs_dir_ialloc(
> xfs_buf_t *ialloc_context = NULL;
> int code;
> void *dqinfo;
> - uint tflags;
>
> tp = *tpp;
> ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
> @@ -1000,12 +999,9 @@ xfs_dir_ialloc(
> * and attach it to the next transaction.
> */
> dqinfo = NULL;
> - tflags = 0;
> if (tp->t_dqinfo) {
> dqinfo = (void *)tp->t_dqinfo;
> tp->t_dqinfo = NULL;
> - tflags = tp->t_flags & XFS_TRANS_DQ_DIRTY;
> - tp->t_flags &= ~(XFS_TRANS_DQ_DIRTY);
> }
>
> code = xfs_trans_roll(&tp);
> @@ -1013,10 +1009,8 @@ xfs_dir_ialloc(
> /*
> * Re-attach the quota info that we detached from prev trx.
> */
> - if (dqinfo) {
> + if (dqinfo)
> tp->t_dqinfo = dqinfo;
> - tp->t_flags |= tflags;
> - }
>
> if (code) {
> xfs_buf_relse(ialloc_context);
> diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
> index fe45b0c3970c..0ebfd7930382 100644
> --- a/fs/xfs/xfs_trans_dquot.c
> +++ b/fs/xfs/xfs_trans_dquot.c
> @@ -84,13 +84,6 @@ xfs_trans_dup_dqinfo(
>
> xfs_trans_alloc_dqinfo(ntp);
>
> - /*
> - * Because the quota blk reservation is carried forward,
> - * it is also necessary to carry forward the DQ_DIRTY flag.
> - */
> - if (otp->t_flags & XFS_TRANS_DQ_DIRTY)
> - ntp->t_flags |= XFS_TRANS_DQ_DIRTY;
> -
> for (j = 0; j < XFS_QM_TRANS_DQTYPES; j++) {
> oqa = otp->t_dqinfo->dqs[j];
> nqa = ntp->t_dqinfo->dqs[j];
> @@ -143,9 +136,6 @@ xfs_trans_mod_dquot_byino(
> xfs_is_quota_inode(&mp->m_sb, ip->i_ino))
> return;
>
> - if (tp->t_dqinfo == NULL)
> - xfs_trans_alloc_dqinfo(tp);
> -
I can't tell from the commit log or from a very quick read of the code why these
allocations are being removed. Can we not get here with a NULL t_dqinfo?
If not, why not? This seems like a change unrelated to the proposed
"t_dqinfo set == XFS_TRANS_DQ_DIRTY" change.
Also, while it seems clear to say that !t_dqinfo == !XFS_TRANS_DQ_DIRTY, is the
converse true? Is it possible to have t_dqinfo set, but it's not dirty?
I think the answer is that when we free the transaction we set t_dqinfo to
NULL again, but I'm not certain, and it's not obvious from the changelog...
-Eric
