* [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops
@ 2017-11-30 17:58 Darrick J. Wong
2017-12-01 13:36 ` Brian Foster
0 siblings, 1 reply; 5+ messages in thread
From: Darrick J. Wong @ 2017-11-30 17:58 UTC (permalink / raw)
To: alex; +Cc: linux-xfs, bfoster, david, libor.klepac
From: Darrick J. Wong <darrick.wong@oracle.com>
In certain cases we need to be able to maintain a buffer lock across a
defer_finish call. Since there could be many (large) transactions
committed as a result of a defer_finish, we have to hold the buffer
across the roll, then immediately rejoin the buffer and mark it dirty in
each transaction to keep the log moving forward.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/libxfs/xfs_defer.c | 37 ++++++++++++++++++++++++++++++++++---
fs/xfs/libxfs/xfs_defer.h | 5 ++++-
2 files changed, 38 insertions(+), 4 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 072ebfe..b5b3414 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -249,6 +249,10 @@ xfs_defer_trans_roll(
for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
xfs_trans_log_inode(*tp, dop->dop_inodes[i], XFS_ILOG_CORE);
+ /* Hold the (previously bjoin'd) buffer locked across the roll. */
+ for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++)
+ xfs_trans_bhold(*tp, dop->dop_bufs[i]);
+
trace_xfs_defer_trans_roll((*tp)->t_mountp, dop);
/* Roll the transaction. */
@@ -264,6 +268,12 @@ xfs_defer_trans_roll(
for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
xfs_trans_ijoin(*tp, dop->dop_inodes[i], 0);
+ /* Rejoin the buffers and dirty them so the log moves forward. */
+ for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++) {
+ xfs_trans_bjoin(*tp, dop->dop_bufs[i]);
+ xfs_trans_dirty_buf(*tp, dop->dop_bufs[i]);
+ }
+
return error;
}
@@ -299,6 +309,29 @@ xfs_defer_ijoin(
}
/*
+ * Add this buffer to the deferred op. Each joined buffer is relogged
+ * each time we roll the transaction.
+ */
+int
+xfs_defer_bjoin(
+ struct xfs_defer_ops *dop,
+ struct xfs_buf *bp)
+{
+ int i;
+
+ for (i = 0; i < XFS_DEFER_OPS_NR_BUFS; i++) {
+ if (dop->dop_bufs[i] == bp)
+ return 0;
+ else if (dop->dop_bufs[i] == NULL) {
+ dop->dop_bufs[i] = bp;
+ return 0;
+ }
+ }
+
+ return -EFSCORRUPTED;
+}
+
+/*
* Finish all the pending work. This involves logging intent items for
* any work items that wandered in since the last transaction roll (if
* one has even happened), rolling the transaction, and finishing the
@@ -493,9 +526,7 @@ xfs_defer_init(
struct xfs_defer_ops *dop,
xfs_fsblock_t *fbp)
{
- dop->dop_committed = false;
- dop->dop_low = false;
- memset(&dop->dop_inodes, 0, sizeof(dop->dop_inodes));
+ memset(dop, 0, sizeof(struct xfs_defer_ops));
*fbp = NULLFSBLOCK;
INIT_LIST_HEAD(&dop->dop_intake);
INIT_LIST_HEAD(&dop->dop_pending);
diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
index d4f046d..045beac 100644
--- a/fs/xfs/libxfs/xfs_defer.h
+++ b/fs/xfs/libxfs/xfs_defer.h
@@ -59,6 +59,7 @@ enum xfs_defer_ops_type {
};
#define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
+#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
struct xfs_defer_ops {
bool dop_committed; /* did any trans commit? */
@@ -66,8 +67,9 @@ struct xfs_defer_ops {
struct list_head dop_intake; /* unlogged pending work */
struct list_head dop_pending; /* logged pending work */
- /* relog these inodes with each roll */
+ /* relog these with each roll */
struct xfs_inode *dop_inodes[XFS_DEFER_OPS_NR_INODES];
+ struct xfs_buf *dop_bufs[XFS_DEFER_OPS_NR_BUFS];
};
void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
@@ -77,6 +79,7 @@ void xfs_defer_cancel(struct xfs_defer_ops *dop);
void xfs_defer_init(struct xfs_defer_ops *dop, xfs_fsblock_t *fbp);
bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
+int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
/* Description of a deferred type. */
struct xfs_defer_op_type {
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops
2017-11-30 17:58 [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops Darrick J. Wong
@ 2017-12-01 13:36 ` Brian Foster
2017-12-01 16:39 ` Darrick J. Wong
0 siblings, 1 reply; 5+ messages in thread
From: Brian Foster @ 2017-12-01 13:36 UTC (permalink / raw)
To: Darrick J. Wong; +Cc: alex, linux-xfs, david, libor.klepac
On Thu, Nov 30, 2017 at 09:58:05AM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> In certain cases we need to be able to maintain a buffer lock across a
> defer_finish call. Since there could be many (large) transactions
> committed as a result of a defer_finish, we have to hold the buffer
> across the roll, then immediately rejoin the buffer and mark it dirty in
> each transaction to keep the log moving forward.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
Seems about right to me. A couple things..
> fs/xfs/libxfs/xfs_defer.c | 37 ++++++++++++++++++++++++++++++++++---
> fs/xfs/libxfs/xfs_defer.h | 5 ++++-
> 2 files changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> index 072ebfe..b5b3414 100644
> --- a/fs/xfs/libxfs/xfs_defer.c
> +++ b/fs/xfs/libxfs/xfs_defer.c
> @@ -249,6 +249,10 @@ xfs_defer_trans_roll(
> for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> xfs_trans_log_inode(*tp, dop->dop_inodes[i], XFS_ILOG_CORE);
>
> + /* Hold the (previously bjoin'd) buffer locked across the roll. */
> + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++)
> + xfs_trans_bhold(*tp, dop->dop_bufs[i]);
> +
It seems more consistent to dirty the buffer in the tx here and
bjoin+bhold it in the loop below.
> trace_xfs_defer_trans_roll((*tp)->t_mountp, dop);
>
> /* Roll the transaction. */
> @@ -264,6 +268,12 @@ xfs_defer_trans_roll(
> for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> xfs_trans_ijoin(*tp, dop->dop_inodes[i], 0);
>
> + /* Rejoin the buffers and dirty them so the log moves forward. */
> + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++) {
> + xfs_trans_bjoin(*tp, dop->dop_bufs[i]);
> + xfs_trans_dirty_buf(*tp, dop->dop_bufs[i]);
> + }
> +
> return error;
> }
>
> @@ -299,6 +309,29 @@ xfs_defer_ijoin(
> }
>
> /*
> + * Add this buffer to the deferred op. Each joined buffer is relogged
> + * each time we roll the transaction.
> + */
> +int
> +xfs_defer_bjoin(
> + struct xfs_defer_ops *dop,
> + struct xfs_buf *bp)
> +{
> + int i;
> +
> + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS; i++) {
> + if (dop->dop_bufs[i] == bp)
> + return 0;
> + else if (dop->dop_bufs[i] == NULL) {
> + dop->dop_bufs[i] = bp;
> + return 0;
> + }
> + }
> +
> + return -EFSCORRUPTED;
I notice that this looks exactly like xfs_defer_join(), but is
-EFSCORRUPTED the right error here? It probably doesn't matter that much
given that if we hit this we've already lost, but I wonder if an error
that more reflects a programming error as opposed to inconsistent fs
might be more appropriate..? -EINVAL, -EBUSY?
Brian
> +}
> +
> +/*
> * Finish all the pending work. This involves logging intent items for
> * any work items that wandered in since the last transaction roll (if
> * one has even happened), rolling the transaction, and finishing the
> @@ -493,9 +526,7 @@ xfs_defer_init(
> struct xfs_defer_ops *dop,
> xfs_fsblock_t *fbp)
> {
> - dop->dop_committed = false;
> - dop->dop_low = false;
> - memset(&dop->dop_inodes, 0, sizeof(dop->dop_inodes));
> + memset(dop, 0, sizeof(struct xfs_defer_ops));
> *fbp = NULLFSBLOCK;
> INIT_LIST_HEAD(&dop->dop_intake);
> INIT_LIST_HEAD(&dop->dop_pending);
> diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> index d4f046d..045beac 100644
> --- a/fs/xfs/libxfs/xfs_defer.h
> +++ b/fs/xfs/libxfs/xfs_defer.h
> @@ -59,6 +59,7 @@ enum xfs_defer_ops_type {
> };
>
> #define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
> +#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
>
> struct xfs_defer_ops {
> bool dop_committed; /* did any trans commit? */
> @@ -66,8 +67,9 @@ struct xfs_defer_ops {
> struct list_head dop_intake; /* unlogged pending work */
> struct list_head dop_pending; /* logged pending work */
>
> - /* relog these inodes with each roll */
> + /* relog these with each roll */
> struct xfs_inode *dop_inodes[XFS_DEFER_OPS_NR_INODES];
> + struct xfs_buf *dop_bufs[XFS_DEFER_OPS_NR_BUFS];
> };
>
> void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
> @@ -77,6 +79,7 @@ void xfs_defer_cancel(struct xfs_defer_ops *dop);
> void xfs_defer_init(struct xfs_defer_ops *dop, xfs_fsblock_t *fbp);
> bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
> int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
> +int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
>
> /* Description of a deferred type. */
> struct xfs_defer_op_type {
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops
2017-12-01 13:36 ` Brian Foster
@ 2017-12-01 16:39 ` Darrick J. Wong
2017-12-01 17:36 ` Brian Foster
0 siblings, 1 reply; 5+ messages in thread
From: Darrick J. Wong @ 2017-12-01 16:39 UTC (permalink / raw)
To: Brian Foster; +Cc: alex, linux-xfs, david, libor.klepac
On Fri, Dec 01, 2017 at 08:36:19AM -0500, Brian Foster wrote:
> On Thu, Nov 30, 2017 at 09:58:05AM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> >
> > In certain cases we need to be able to maintain a buffer lock across a
> > defer_finish call. Since there could be many (large) transactions
> > committed as a result of a defer_finish, we have to hold the buffer
> > across the roll, then immediately rejoin the buffer and mark it dirty in
> > each transaction to keep the log moving forward.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
>
> Seems about right to me. A couple things..
>
> > fs/xfs/libxfs/xfs_defer.c | 37 ++++++++++++++++++++++++++++++++++---
> > fs/xfs/libxfs/xfs_defer.h | 5 ++++-
> > 2 files changed, 38 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> > index 072ebfe..b5b3414 100644
> > --- a/fs/xfs/libxfs/xfs_defer.c
> > +++ b/fs/xfs/libxfs/xfs_defer.c
> > @@ -249,6 +249,10 @@ xfs_defer_trans_roll(
> > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > xfs_trans_log_inode(*tp, dop->dop_inodes[i], XFS_ILOG_CORE);
> >
> > + /* Hold the (previously bjoin'd) buffer locked across the roll. */
> > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++)
> > + xfs_trans_bhold(*tp, dop->dop_bufs[i]);
> > +
>
> It seems more consistent to dirty the buffer in the tx here and
> bjoin+bhold it in the loop below.
I thought the purpose of calling bhold was to prevent the transaction
commit (in xfs_trans_roll) from unlocking the buffer? Therefore you'd
bhold it before the _roll and then bjoin/dirty the still-locked buffer
afterwards to attach the buffer as a dirty buffer to the new
transaction.
> > trace_xfs_defer_trans_roll((*tp)->t_mountp, dop);
> >
> > /* Roll the transaction. */
> > @@ -264,6 +268,12 @@ xfs_defer_trans_roll(
> > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > xfs_trans_ijoin(*tp, dop->dop_inodes[i], 0);
> >
> > + /* Rejoin the buffers and dirty them so the log moves forward. */
> > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++) {
> > + xfs_trans_bjoin(*tp, dop->dop_bufs[i]);
> > + xfs_trans_dirty_buf(*tp, dop->dop_bufs[i]);
> > + }
> > +
> > return error;
> > }
> >
> > @@ -299,6 +309,29 @@ xfs_defer_ijoin(
> > }
> >
> > /*
> > + * Add this buffer to the deferred op. Each joined buffer is relogged
> > + * each time we roll the transaction.
> > + */
> > +int
> > +xfs_defer_bjoin(
> > + struct xfs_defer_ops *dop,
> > + struct xfs_buf *bp)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS; i++) {
> > + if (dop->dop_bufs[i] == bp)
> > + return 0;
> > + else if (dop->dop_bufs[i] == NULL) {
> > + dop->dop_bufs[i] = bp;
> > + return 0;
> > + }
> > + }
> > +
> > + return -EFSCORRUPTED;
>
> I notice that this looks exactly like xfs_defer_join(), but is
> -EFSCORRUPTED the right error here? It probably doesn't matter that much
> given that if we hit this we've already lost, but I wonder if an error
> that more reflects a programming error as opposed to inconsistent fs
> might be more appropriate..? -EINVAL, -EBUSY?
Yeah, I'm not sure what error code applies to "programmer messed up" :)
Perhaps we should add an ASSERT(0) at the bottom of both functions.
--D
> Brian
>
> > +}
> > +
> > +/*
> > * Finish all the pending work. This involves logging intent items for
> > * any work items that wandered in since the last transaction roll (if
> > * one has even happened), rolling the transaction, and finishing the
> > @@ -493,9 +526,7 @@ xfs_defer_init(
> > struct xfs_defer_ops *dop,
> > xfs_fsblock_t *fbp)
> > {
> > - dop->dop_committed = false;
> > - dop->dop_low = false;
> > - memset(&dop->dop_inodes, 0, sizeof(dop->dop_inodes));
> > + memset(dop, 0, sizeof(struct xfs_defer_ops));
> > *fbp = NULLFSBLOCK;
> > INIT_LIST_HEAD(&dop->dop_intake);
> > INIT_LIST_HEAD(&dop->dop_pending);
> > diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> > index d4f046d..045beac 100644
> > --- a/fs/xfs/libxfs/xfs_defer.h
> > +++ b/fs/xfs/libxfs/xfs_defer.h
> > @@ -59,6 +59,7 @@ enum xfs_defer_ops_type {
> > };
> >
> > #define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
> > +#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
> >
> > struct xfs_defer_ops {
> > bool dop_committed; /* did any trans commit? */
> > @@ -66,8 +67,9 @@ struct xfs_defer_ops {
> > struct list_head dop_intake; /* unlogged pending work */
> > struct list_head dop_pending; /* logged pending work */
> >
> > - /* relog these inodes with each roll */
> > + /* relog these with each roll */
> > struct xfs_inode *dop_inodes[XFS_DEFER_OPS_NR_INODES];
> > + struct xfs_buf *dop_bufs[XFS_DEFER_OPS_NR_BUFS];
> > };
> >
> > void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
> > @@ -77,6 +79,7 @@ void xfs_defer_cancel(struct xfs_defer_ops *dop);
> > void xfs_defer_init(struct xfs_defer_ops *dop, xfs_fsblock_t *fbp);
> > bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
> > int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
> > +int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
> >
> > /* Description of a deferred type. */
> > struct xfs_defer_op_type {
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops
2017-12-01 16:39 ` Darrick J. Wong
@ 2017-12-01 17:36 ` Brian Foster
2017-12-07 0:35 ` Darrick J. Wong
0 siblings, 1 reply; 5+ messages in thread
From: Brian Foster @ 2017-12-01 17:36 UTC (permalink / raw)
To: Darrick J. Wong; +Cc: alex, linux-xfs, david, libor.klepac
On Fri, Dec 01, 2017 at 08:39:44AM -0800, Darrick J. Wong wrote:
> On Fri, Dec 01, 2017 at 08:36:19AM -0500, Brian Foster wrote:
> > On Thu, Nov 30, 2017 at 09:58:05AM -0800, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > >
> > > In certain cases we need to be able to maintain a buffer lock across a
> > > defer_finish call. Since there could be many (large) transactions
> > > committed as a result of a defer_finish, we have to hold the buffer
> > > across the roll, then immediately rejoin the buffer and mark it dirty in
> > > each transaction to keep the log moving forward.
> > >
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > ---
> >
> > Seems about right to me. A couple things..
> >
> > > fs/xfs/libxfs/xfs_defer.c | 37 ++++++++++++++++++++++++++++++++++---
> > > fs/xfs/libxfs/xfs_defer.h | 5 ++++-
> > > 2 files changed, 38 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> > > index 072ebfe..b5b3414 100644
> > > --- a/fs/xfs/libxfs/xfs_defer.c
> > > +++ b/fs/xfs/libxfs/xfs_defer.c
> > > @@ -249,6 +249,10 @@ xfs_defer_trans_roll(
> > > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > > xfs_trans_log_inode(*tp, dop->dop_inodes[i], XFS_ILOG_CORE);
> > >
> > > + /* Hold the (previously bjoin'd) buffer locked across the roll. */
> > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++)
> > > + xfs_trans_bhold(*tp, dop->dop_bufs[i]);
> > > +
> >
> > It seems more consistent to dirty the buffer in the tx here and
> > bjoin+bhold it in the loop below.
>
> I thought the purpose of calling bhold was to prevent the transaction
> commit (in xfs_trans_roll) from unlocking the buffer? Therefore you'd
> bhold it before the _roll and then bjoin/dirty the still-locked buffer
> afterwards to attach the buffer as a dirty buffer to the new
> transaction.
>
Yeah, but that wouldn't necessarily change.. I guess what I overlooked
before is that xfs_defer_bjoin() doesn't actually hold the buffer in the
current tp, so we'd have to start off with call to do that in the
current transaction. All in all, what throws me off a bit is that I'd
expect the same semantics/behavior for buffers in this situation as we
have for inodes...
xfs_attr_set() joins the inode the transaction without transferring the
lock (which is analogous to _bjoin() + _bhold()). It does some real
work, defer_ijoin()'s the inode and finishes deferred ops.
xfs_defer_finish() ultimately returns with a transaction that holds the
inode with a clean log item descriptor.
The analogous behavior for buffers in my mind is for xfs_attr_set() to
bhold the buffer to the current transaction, defer_bjoin() it and
ultimately return from xfs_defer_finish() with the buffer held, but not
yet dirtied, in the current transaction. Hm?
Brian
> > > trace_xfs_defer_trans_roll((*tp)->t_mountp, dop);
> > >
> > > /* Roll the transaction. */
> > > @@ -264,6 +268,12 @@ xfs_defer_trans_roll(
> > > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > > xfs_trans_ijoin(*tp, dop->dop_inodes[i], 0);
> > >
> > > + /* Rejoin the buffers and dirty them so the log moves forward. */
> > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++) {
> > > + xfs_trans_bjoin(*tp, dop->dop_bufs[i]);
> > > + xfs_trans_dirty_buf(*tp, dop->dop_bufs[i]);
> > > + }
> > > +
> > > return error;
> > > }
> > >
> > > @@ -299,6 +309,29 @@ xfs_defer_ijoin(
> > > }
> > >
> > > /*
> > > + * Add this buffer to the deferred op. Each joined buffer is relogged
> > > + * each time we roll the transaction.
> > > + */
> > > +int
> > > +xfs_defer_bjoin(
> > > + struct xfs_defer_ops *dop,
> > > + struct xfs_buf *bp)
> > > +{
> > > + int i;
> > > +
> > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS; i++) {
> > > + if (dop->dop_bufs[i] == bp)
> > > + return 0;
> > > + else if (dop->dop_bufs[i] == NULL) {
> > > + dop->dop_bufs[i] = bp;
> > > + return 0;
> > > + }
> > > + }
> > > +
> > > + return -EFSCORRUPTED;
> >
> > I notice that this looks exactly like xfs_defer_join(), but is
> > -EFSCORRUPTED the right error here? It probably doesn't matter that much
> > given that if we hit this we've already lost, but I wonder if an error
> > that more reflects a programming error as opposed to inconsistent fs
> > might be more appropriate..? -EINVAL, -EBUSY?
>
> Yeah, I'm not sure what error code applies to "programmer messed up" :)
>
> Perhaps we should add an ASSERT(0) at the bottom of both functions.
>
> --D
>
> > Brian
> >
> > > +}
> > > +
> > > +/*
> > > * Finish all the pending work. This involves logging intent items for
> > > * any work items that wandered in since the last transaction roll (if
> > > * one has even happened), rolling the transaction, and finishing the
> > > @@ -493,9 +526,7 @@ xfs_defer_init(
> > > struct xfs_defer_ops *dop,
> > > xfs_fsblock_t *fbp)
> > > {
> > > - dop->dop_committed = false;
> > > - dop->dop_low = false;
> > > - memset(&dop->dop_inodes, 0, sizeof(dop->dop_inodes));
> > > + memset(dop, 0, sizeof(struct xfs_defer_ops));
> > > *fbp = NULLFSBLOCK;
> > > INIT_LIST_HEAD(&dop->dop_intake);
> > > INIT_LIST_HEAD(&dop->dop_pending);
> > > diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> > > index d4f046d..045beac 100644
> > > --- a/fs/xfs/libxfs/xfs_defer.h
> > > +++ b/fs/xfs/libxfs/xfs_defer.h
> > > @@ -59,6 +59,7 @@ enum xfs_defer_ops_type {
> > > };
> > >
> > > #define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
> > > +#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
> > >
> > > struct xfs_defer_ops {
> > > bool dop_committed; /* did any trans commit? */
> > > @@ -66,8 +67,9 @@ struct xfs_defer_ops {
> > > struct list_head dop_intake; /* unlogged pending work */
> > > struct list_head dop_pending; /* logged pending work */
> > >
> > > - /* relog these inodes with each roll */
> > > + /* relog these with each roll */
> > > struct xfs_inode *dop_inodes[XFS_DEFER_OPS_NR_INODES];
> > > + struct xfs_buf *dop_bufs[XFS_DEFER_OPS_NR_BUFS];
> > > };
> > >
> > > void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
> > > @@ -77,6 +79,7 @@ void xfs_defer_cancel(struct xfs_defer_ops *dop);
> > > void xfs_defer_init(struct xfs_defer_ops *dop, xfs_fsblock_t *fbp);
> > > bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
> > > int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
> > > +int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
> > >
> > > /* Description of a deferred type. */
> > > struct xfs_defer_op_type {
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops
2017-12-01 17:36 ` Brian Foster
@ 2017-12-07 0:35 ` Darrick J. Wong
0 siblings, 0 replies; 5+ messages in thread
From: Darrick J. Wong @ 2017-12-07 0:35 UTC (permalink / raw)
To: Brian Foster; +Cc: alex, linux-xfs, david, libor.klepac
On Fri, Dec 01, 2017 at 12:36:56PM -0500, Brian Foster wrote:
> On Fri, Dec 01, 2017 at 08:39:44AM -0800, Darrick J. Wong wrote:
> > On Fri, Dec 01, 2017 at 08:36:19AM -0500, Brian Foster wrote:
> > > On Thu, Nov 30, 2017 at 09:58:05AM -0800, Darrick J. Wong wrote:
> > > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > > >
> > > > In certain cases we need to be able to maintain a buffer lock across a
> > > > defer_finish call. Since there could be many (large) transactions
> > > > committed as a result of a defer_finish, we have to hold the buffer
> > > > across the roll, then immediately rejoin the buffer and mark it dirty in
> > > > each transaction to keep the log moving forward.
> > > >
> > > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > > > ---
> > >
> > > Seems about right to me. A couple things..
> > >
> > > > fs/xfs/libxfs/xfs_defer.c | 37 ++++++++++++++++++++++++++++++++++---
> > > > fs/xfs/libxfs/xfs_defer.h | 5 ++++-
> > > > 2 files changed, 38 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
> > > > index 072ebfe..b5b3414 100644
> > > > --- a/fs/xfs/libxfs/xfs_defer.c
> > > > +++ b/fs/xfs/libxfs/xfs_defer.c
> > > > @@ -249,6 +249,10 @@ xfs_defer_trans_roll(
> > > > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > > > xfs_trans_log_inode(*tp, dop->dop_inodes[i], XFS_ILOG_CORE);
> > > >
> > > > + /* Hold the (previously bjoin'd) buffer locked across the roll. */
> > > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++)
> > > > + xfs_trans_bhold(*tp, dop->dop_bufs[i]);
> > > > +
> > >
> > > It seems more consistent to dirty the buffer in the tx here and
> > > bjoin+bhold it in the loop below.
> >
> > I thought the purpose of calling bhold was to prevent the transaction
> > commit (in xfs_trans_roll) from unlocking the buffer? Therefore you'd
> > bhold it before the _roll and then bjoin/dirty the still-locked buffer
> > afterwards to attach the buffer as a dirty buffer to the new
> > transaction.
> >
>
> Yeah, but that wouldn't necessarily change.. I guess what I overlooked
> before is that xfs_defer_bjoin() doesn't actually hold the buffer in the
> current tp, so we'd have to start off with call to do that in the
> current transaction. All in all, what throws me off a bit is that I'd
> expect the same semantics/behavior for buffers in this situation as we
> have for inodes...
>
> xfs_attr_set() joins the inode the transaction without transferring the
> lock (which is analogous to _bjoin() + _bhold()). It does some real
> work, defer_ijoin()'s the inode and finishes deferred ops.
> xfs_defer_finish() ultimately returns with a transaction that holds the
> inode with a clean log item descriptor.
>
> The analogous behavior for buffers in my mind is for xfs_attr_set() to
> bhold the buffer to the current transaction, defer_bjoin() it and
> ultimately return from xfs_defer_finish() with the buffer held, but not
> yet dirtied, in the current transaction. Hm?
Ahhh, ok. In my head I had designed this as "I have this locked buffer,
now do whatever you have to do to ensure that it doesn't get unlocked in
defer_finish." whereas the strategy for inodes is "I have this locked
inode that won't unlock until I tell it to, so do whatever you must to
ensure that it gets relogged in defer_finish and is still
locked-and-wont-unlock."
I can do the same with buffers -- "I have this locked buffer that won't
unlock until I tell it to, so do what you have to do to ensure it gets
relogged and is still locked-and-wont-unlock after defer_finish."
--D
> Brian
>
> > > > trace_xfs_defer_trans_roll((*tp)->t_mountp, dop);
> > > >
> > > > /* Roll the transaction. */
> > > > @@ -264,6 +268,12 @@ xfs_defer_trans_roll(
> > > > for (i = 0; i < XFS_DEFER_OPS_NR_INODES && dop->dop_inodes[i]; i++)
> > > > xfs_trans_ijoin(*tp, dop->dop_inodes[i], 0);
> > > >
> > > > + /* Rejoin the buffers and dirty them so the log moves forward. */
> > > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS && dop->dop_bufs[i]; i++) {
> > > > + xfs_trans_bjoin(*tp, dop->dop_bufs[i]);
> > > > + xfs_trans_dirty_buf(*tp, dop->dop_bufs[i]);
> > > > + }
> > > > +
> > > > return error;
> > > > }
> > > >
> > > > @@ -299,6 +309,29 @@ xfs_defer_ijoin(
> > > > }
> > > >
> > > > /*
> > > > + * Add this buffer to the deferred op. Each joined buffer is relogged
> > > > + * each time we roll the transaction.
> > > > + */
> > > > +int
> > > > +xfs_defer_bjoin(
> > > > + struct xfs_defer_ops *dop,
> > > > + struct xfs_buf *bp)
> > > > +{
> > > > + int i;
> > > > +
> > > > + for (i = 0; i < XFS_DEFER_OPS_NR_BUFS; i++) {
> > > > + if (dop->dop_bufs[i] == bp)
> > > > + return 0;
> > > > + else if (dop->dop_bufs[i] == NULL) {
> > > > + dop->dop_bufs[i] = bp;
> > > > + return 0;
> > > > + }
> > > > + }
> > > > +
> > > > + return -EFSCORRUPTED;
> > >
> > > I notice that this looks exactly like xfs_defer_join(), but is
> > > -EFSCORRUPTED the right error here? It probably doesn't matter that much
> > > given that if we hit this we've already lost, but I wonder if an error
> > > that more reflects a programming error as opposed to inconsistent fs
> > > might be more appropriate..? -EINVAL, -EBUSY?
> >
> > Yeah, I'm not sure what error code applies to "programmer messed up" :)
> >
> > Perhaps we should add an ASSERT(0) at the bottom of both functions.
> >
> > --D
> >
> > > Brian
> > >
> > > > +}
> > > > +
> > > > +/*
> > > > * Finish all the pending work. This involves logging intent items for
> > > > * any work items that wandered in since the last transaction roll (if
> > > > * one has even happened), rolling the transaction, and finishing the
> > > > @@ -493,9 +526,7 @@ xfs_defer_init(
> > > > struct xfs_defer_ops *dop,
> > > > xfs_fsblock_t *fbp)
> > > > {
> > > > - dop->dop_committed = false;
> > > > - dop->dop_low = false;
> > > > - memset(&dop->dop_inodes, 0, sizeof(dop->dop_inodes));
> > > > + memset(dop, 0, sizeof(struct xfs_defer_ops));
> > > > *fbp = NULLFSBLOCK;
> > > > INIT_LIST_HEAD(&dop->dop_intake);
> > > > INIT_LIST_HEAD(&dop->dop_pending);
> > > > diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h
> > > > index d4f046d..045beac 100644
> > > > --- a/fs/xfs/libxfs/xfs_defer.h
> > > > +++ b/fs/xfs/libxfs/xfs_defer.h
> > > > @@ -59,6 +59,7 @@ enum xfs_defer_ops_type {
> > > > };
> > > >
> > > > #define XFS_DEFER_OPS_NR_INODES 2 /* join up to two inodes */
> > > > +#define XFS_DEFER_OPS_NR_BUFS 2 /* join up to two buffers */
> > > >
> > > > struct xfs_defer_ops {
> > > > bool dop_committed; /* did any trans commit? */
> > > > @@ -66,8 +67,9 @@ struct xfs_defer_ops {
> > > > struct list_head dop_intake; /* unlogged pending work */
> > > > struct list_head dop_pending; /* logged pending work */
> > > >
> > > > - /* relog these inodes with each roll */
> > > > + /* relog these with each roll */
> > > > struct xfs_inode *dop_inodes[XFS_DEFER_OPS_NR_INODES];
> > > > + struct xfs_buf *dop_bufs[XFS_DEFER_OPS_NR_BUFS];
> > > > };
> > > >
> > > > void xfs_defer_add(struct xfs_defer_ops *dop, enum xfs_defer_ops_type type,
> > > > @@ -77,6 +79,7 @@ void xfs_defer_cancel(struct xfs_defer_ops *dop);
> > > > void xfs_defer_init(struct xfs_defer_ops *dop, xfs_fsblock_t *fbp);
> > > > bool xfs_defer_has_unfinished_work(struct xfs_defer_ops *dop);
> > > > int xfs_defer_ijoin(struct xfs_defer_ops *dop, struct xfs_inode *ip);
> > > > +int xfs_defer_bjoin(struct xfs_defer_ops *dop, struct xfs_buf *bp);
> > > >
> > > > /* Description of a deferred type. */
> > > > struct xfs_defer_op_type {
> > > > --
> > > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > > the body of a message to majordomo@vger.kernel.org
> > > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-12-07 0:35 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2017-11-30 17:58 [RFC PATCH 1/2] xfs: add the ability to join a buffer to a defer_ops Darrick J. Wong
2017-12-01 13:36 ` Brian Foster
2017-12-01 16:39 ` Darrick J. Wong
2017-12-01 17:36 ` Brian Foster
2017-12-07 0:35 ` Darrick J. Wong
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