While reviewing whether MAP_SYNC should strengthen its current guarantee
of syncing writes from the initiating process to also include
third-party readers observing dirty metadata, Dave pointed out that the
check of IOMAP_WRITE is misplaced.
The policy of what to with IOMAP_F_DIRTY should be separated from the
generic filesystem mechanism of reporting dirty metadata. Move this
policy to the fs-dax core to simplify the per-filesystem iomap handlers,
and further centralize code that implements the MAP_SYNC policy. This
otherwise should not change behavior, it just makes it easier to change
behavior in the future.
Cc: Jan Kara <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Ross Zwisler <[email protected]>
Reported-by: Dave Chinner <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
---
This is an additional cleanup I want to include in the 4.15 merge
request for the MAP_SYNC feature. Please review, I'm looking to send the
pull request towards the end of the week.
fs/dax.c | 15 +++++++++++++--
fs/ext4/inode.c | 2 +-
fs/xfs/xfs_iomap.c | 6 +++---
3 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 78233c716757..27ba300660ff 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1079,6 +1079,17 @@ static int dax_fault_return(int error)
return VM_FAULT_SIGBUS;
}
+/*
+ * MAP_SYNC on a dax mapping guarantees dirty metadata is
+ * flushed on write-faults (non-cow), but not read-faults.
+ */
+static bool dax_fault_is_synchronous(unsigned long flags,
+ struct vm_area_struct *vma, struct iomap *iomap)
+{
+ return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
+ && (iomap->flags & IOMAP_F_DIRTY);
+}
+
static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
const struct iomap_ops *ops)
{
@@ -1170,7 +1181,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto finish_iomap;
}
- sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
+ sync = dax_fault_is_synchronous(flags, vma, &iomap);
switch (iomap.type) {
case IOMAP_MAPPED:
@@ -1390,7 +1401,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
if (iomap.offset + iomap.length < pos + PMD_SIZE)
goto finish_iomap;
- sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
+ sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap);
switch (iomap.type) {
case IOMAP_MAPPED:
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 13a198924a0f..ee4d907a4251 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3479,7 +3479,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}
iomap->flags = 0;
- if ((flags & IOMAP_WRITE) && ext4_inode_datasync_dirty(inode))
+ if (ext4_inode_datasync_dirty(inode))
iomap->flags |= IOMAP_F_DIRTY;
iomap->bdev = inode->i_sb->s_bdev;
iomap->dax_dev = sbi->s_daxdev;
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index b43be199fbdf..888b60189983 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1087,9 +1087,9 @@ xfs_file_iomap_begin(
trace_xfs_iomap_found(ip, offset, length, 0, &imap);
}
- if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
- (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
- iomap->flags |= IOMAP_F_DIRTY;
+ if (xfs_ipincount(ip))
+ if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
+ iomap->flags |= IOMAP_F_DIRTY;
xfs_bmbt_to_iomap(ip, iomap, &imap);
On Mon, Nov 13, 2017 at 05:27:54PM -0800, Dan Williams wrote:
> While reviewing whether MAP_SYNC should strengthen its current guarantee
> of syncing writes from the initiating process to also include
> third-party readers observing dirty metadata, Dave pointed out that the
> check of IOMAP_WRITE is misplaced.
>
> The policy of what to with IOMAP_F_DIRTY should be separated from the
> generic filesystem mechanism of reporting dirty metadata. Move this
> policy to the fs-dax core to simplify the per-filesystem iomap handlers,
> and further centralize code that implements the MAP_SYNC policy. This
> otherwise should not change behavior, it just makes it easier to change
> behavior in the future.
Yes, this was what I was looking for on my last read-through. :)
> Cc: Jan Kara <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Darrick J. Wong <[email protected]>
> Cc: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/[email protected]>
> Reported-by: Dave Chinner <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
> ---
> This is an additional cleanup I want to include in the 4.15 merge
> request for the MAP_SYNC feature. Please review, I'm looking to send the
> pull request towards the end of the week.
>
>
> fs/dax.c | 15 +++++++++++++--
> fs/ext4/inode.c | 2 +-
> fs/xfs/xfs_iomap.c | 6 +++---
> 3 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 78233c716757..27ba300660ff 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1079,6 +1079,17 @@ static int dax_fault_return(int error)
> return VM_FAULT_SIGBUS;
> }
>
> +/*
> + * MAP_SYNC on a dax mapping guarantees dirty metadata is
> + * flushed on write-faults (non-cow), but not read-faults.
> + */
> +static bool dax_fault_is_synchronous(unsigned long flags,
> + struct vm_area_struct *vma, struct iomap *iomap)
> +{
> + return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
> + && (iomap->flags & IOMAP_F_DIRTY);
> +}
> +
> static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> const struct iomap_ops *ops)
> {
> @@ -1170,7 +1181,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> goto finish_iomap;
> }
>
> - sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
> + sync = dax_fault_is_synchronous(flags, vma, &iomap);
>
> switch (iomap.type) {
> case IOMAP_MAPPED:
> @@ -1390,7 +1401,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> if (iomap.offset + iomap.length < pos + PMD_SIZE)
> goto finish_iomap;
>
> - sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
> + sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap);
>
> switch (iomap.type) {
> case IOMAP_MAPPED:
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 13a198924a0f..ee4d907a4251 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3479,7 +3479,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> }
>
> iomap->flags = 0;
> - if ((flags & IOMAP_WRITE) && ext4_inode_datasync_dirty(inode))
> + if (ext4_inode_datasync_dirty(inode))
> iomap->flags |= IOMAP_F_DIRTY;
> iomap->bdev = inode->i_sb->s_bdev;
> iomap->dax_dev = sbi->s_daxdev;
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index b43be199fbdf..888b60189983 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1087,9 +1087,9 @@ xfs_file_iomap_begin(
> trace_xfs_iomap_found(ip, offset, length, 0, &imap);
> }
>
> - if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
> - (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
> - iomap->flags |= IOMAP_F_DIRTY;
> + if (xfs_ipincount(ip))
> + if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
Why not if (xfs_ipincount(ip) && (ip->... & ~XFS_ILOG_TIMESTAMP)) ?
Otherwise looks ok (just this patch, will rvb the rest separately),
Reviewed-by: Darrick J. Wong <[email protected]>
--D
> + iomap->flags |= IOMAP_F_DIRTY;
>
> xfs_bmbt_to_iomap(ip, iomap, &imap);
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Nov 13, 2017 at 05:27:54PM -0800, Dan Williams wrote:
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index b43be199fbdf..888b60189983 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1087,9 +1087,9 @@ xfs_file_iomap_begin(
> trace_xfs_iomap_found(ip, offset, length, 0, &imap);
> }
>
> - if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
> - (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
> - iomap->flags |= IOMAP_F_DIRTY;
> + if (xfs_ipincount(ip))
> + if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
> + iomap->flags |= IOMAP_F_DIRTY;
Please make a helper for this, and use it in xfs_file_fsync() where
the same dirty checks are done. e.g.
static inline bool
xfs_inode_need_fsync(struct xfs_inode *ip, bool datasync)
{
if (!xfs_ipincount(ip))
return false;
if (xfs_inode_clean(ip))
return false;
if (datasync &&
!(ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
return false;
return true;
}
Cheers,
Dave.
--
Dave Chinner
[email protected]
> - if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
> - (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
> - iomap->flags |= IOMAP_F_DIRTY;
> + if (xfs_ipincount(ip))
> + if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
> + iomap->flags |= IOMAP_F_DIRTY;
Please don't split up the conditional and make it harder to read.
With that fixed up this looks fine to me:
Reviewed-by: Christoph Hellwig <[email protected]>
On Tue, Nov 14, 2017 at 03:12:28PM +1100, Dave Chinner wrote:
> On Mon, Nov 13, 2017 at 05:27:54PM -0800, Dan Williams wrote:
> > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> > index b43be199fbdf..888b60189983 100644
> > --- a/fs/xfs/xfs_iomap.c
> > +++ b/fs/xfs/xfs_iomap.c
> > @@ -1087,9 +1087,9 @@ xfs_file_iomap_begin(
> > trace_xfs_iomap_found(ip, offset, length, 0, &imap);
> > }
> >
> > - if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
> > - (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
> > - iomap->flags |= IOMAP_F_DIRTY;
> > + if (xfs_ipincount(ip))
> > + if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
> > + iomap->flags |= IOMAP_F_DIRTY;
>
> Please make a helper for this, and use it in xfs_file_fsync() where
> the same dirty checks are done. e.g.
Let's keep that sort of cleanup separate. I initially considered
it when doing the MAP_SYNC work, but fsync works a little different
in that it looks at ili_last_lsn, so your little helper below won't
work as-is. You can send it as an incremental patch later and we
can see if we can come up with something workable.
On Mon 13-11-17 17:27:54, Dan Williams wrote:
> While reviewing whether MAP_SYNC should strengthen its current guarantee
> of syncing writes from the initiating process to also include
> third-party readers observing dirty metadata, Dave pointed out that the
> check of IOMAP_WRITE is misplaced.
>
> The policy of what to with IOMAP_F_DIRTY should be separated from the
> generic filesystem mechanism of reporting dirty metadata. Move this
> policy to the fs-dax core to simplify the per-filesystem iomap handlers,
> and further centralize code that implements the MAP_SYNC policy. This
> otherwise should not change behavior, it just makes it easier to change
> behavior in the future.
>
> Cc: Jan Kara <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> Cc: Darrick J. Wong <[email protected]>
> Cc: Ross Zwisler <[email protected]>
> Reported-by: Dave Chinner <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>
> ---
> This is an additional cleanup I want to include in the 4.15 merge
> request for the MAP_SYNC feature. Please review, I'm looking to send the
> pull request towards the end of the week.
The patch looks fine to me. You can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
>
>
> fs/dax.c | 15 +++++++++++++--
> fs/ext4/inode.c | 2 +-
> fs/xfs/xfs_iomap.c | 6 +++---
> 3 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 78233c716757..27ba300660ff 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1079,6 +1079,17 @@ static int dax_fault_return(int error)
> return VM_FAULT_SIGBUS;
> }
>
> +/*
> + * MAP_SYNC on a dax mapping guarantees dirty metadata is
> + * flushed on write-faults (non-cow), but not read-faults.
> + */
> +static bool dax_fault_is_synchronous(unsigned long flags,
> + struct vm_area_struct *vma, struct iomap *iomap)
> +{
> + return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
> + && (iomap->flags & IOMAP_F_DIRTY);
> +}
> +
> static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> const struct iomap_ops *ops)
> {
> @@ -1170,7 +1181,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
> goto finish_iomap;
> }
>
> - sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
> + sync = dax_fault_is_synchronous(flags, vma, &iomap);
>
> switch (iomap.type) {
> case IOMAP_MAPPED:
> @@ -1390,7 +1401,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> if (iomap.offset + iomap.length < pos + PMD_SIZE)
> goto finish_iomap;
>
> - sync = (vma->vm_flags & VM_SYNC) && (iomap.flags & IOMAP_F_DIRTY);
> + sync = dax_fault_is_synchronous(iomap_flags, vma, &iomap);
>
> switch (iomap.type) {
> case IOMAP_MAPPED:
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 13a198924a0f..ee4d907a4251 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3479,7 +3479,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> }
>
> iomap->flags = 0;
> - if ((flags & IOMAP_WRITE) && ext4_inode_datasync_dirty(inode))
> + if (ext4_inode_datasync_dirty(inode))
> iomap->flags |= IOMAP_F_DIRTY;
> iomap->bdev = inode->i_sb->s_bdev;
> iomap->dax_dev = sbi->s_daxdev;
> diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
> index b43be199fbdf..888b60189983 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -1087,9 +1087,9 @@ xfs_file_iomap_begin(
> trace_xfs_iomap_found(ip, offset, length, 0, &imap);
> }
>
> - if ((flags & IOMAP_WRITE) && xfs_ipincount(ip) &&
> - (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
> - iomap->flags |= IOMAP_F_DIRTY;
> + if (xfs_ipincount(ip))
> + if (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP)
> + iomap->flags |= IOMAP_F_DIRTY;
>
> xfs_bmbt_to_iomap(ip, iomap, &imap);
>
>
--
Jan Kara <[email protected]>
SUSE Labs, CR