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Message-ID: <OSBPR01MB2920D2D275EB0DB15C37D079F4079@OSBPR01MB2920.jpnprd01.prod.outlook.com>
Date: Thu, 24 Jun 2021 08:49:17 +0000
From: "ruansy.fnst@...itsu.com" <ruansy.fnst@...itsu.com>
To: "Darrick J. Wong" <djwong@...nel.org>
CC: "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
"david@...morbit.com" <david@...morbit.com>,
"djwong@...nel.org" <djwong@...nel.org>, "hch@....de" <hch@....de>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
"linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
"rgoldwyn@...e.de" <rgoldwyn@...e.de>,
"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
"willy@...radead.org" <willy@...radead.org>
Subject: RE: [PATCH v6.1 6/7] fs/xfs: Handle CoW for fsdax write() path
Hi Darrick,
Do you have any comment on this?
--
Thanks,
Ruan.
> -----Original Message-----
> From: Shiyang Ruan <ruansy.fnst@...itsu.com>
> Subject: [PATCH v6.1 6/7] fs/xfs: Handle CoW for fsdax write() path
>
> Hi Darrick,
>
> Since other patches looks good, I post this RFC patch singly to hot-fix the
> problem in xfs_dax_write_iomap_ops->iomap_end() of v6 that the error code
> was ingored. I will split this in two patches(changes in iomap and xfs
> respectively) in next formal version if it looks ok.
>
> ====
>
> Introduce a new interface called "iomap_post_actor()" in iomap_ops. And call
> it between ->actor() and ->iomap_end(). It is mean to handle the error code
> returned from ->actor(). In this patchset, it is used to remap or cancel the
> CoW extents according to the error code.
>
> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
> ---
> fs/dax.c | 27 ++++++++++++++++++---------
> fs/iomap/apply.c | 4 ++++
> fs/xfs/xfs_bmap_util.c | 3 +--
> fs/xfs/xfs_file.c | 5 +++--
> fs/xfs/xfs_iomap.c | 33 ++++++++++++++++++++++++++++++++-
> fs/xfs/xfs_iomap.h | 24 ++++++++++++++++++++++++
> fs/xfs/xfs_iops.c | 7 +++----
> fs/xfs/xfs_reflink.c | 3 +--
> include/linux/iomap.h | 8 ++++++++
> 9 files changed, 94 insertions(+), 20 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 93f16210847b..0740c2610b6f 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1537,7 +1537,7 @@ static vm_fault_t dax_iomap_pte_fault(struct
> vm_fault *vmf, pfn_t *pfnp,
> struct iomap iomap = { .type = IOMAP_HOLE };
> struct iomap srcmap = { .type = IOMAP_HOLE };
> unsigned flags = IOMAP_FAULT;
> - int error;
> + int error, copied = PAGE_SIZE;
> bool write = vmf->flags & FAULT_FLAG_WRITE;
> vm_fault_t ret = 0, major = 0;
> void *entry;
> @@ -1598,7 +1598,7 @@ static vm_fault_t dax_iomap_pte_fault(struct
> vm_fault *vmf, pfn_t *pfnp,
> ret = dax_fault_actor(vmf, pfnp, &xas, &entry, false, flags,
> &iomap, &srcmap);
> if (ret == VM_FAULT_SIGBUS)
> - goto finish_iomap;
> + goto finish_iomap_actor;
>
> /* read/write MAPPED, CoW UNWRITTEN */
> if (iomap.flags & IOMAP_F_NEW) {
> @@ -1607,10 +1607,16 @@ static vm_fault_t dax_iomap_pte_fault(struct
> vm_fault *vmf, pfn_t *pfnp,
> major = VM_FAULT_MAJOR;
> }
>
> + finish_iomap_actor:
> + if (ops->iomap_post_actor) {
> + if (ret & VM_FAULT_ERROR)
> + copied = 0;
> + ops->iomap_post_actor(inode, pos, PMD_SIZE, copied, flags,
> + &iomap, &srcmap);
> + }
> +
> finish_iomap:
> if (ops->iomap_end) {
> - int copied = PAGE_SIZE;
> -
> if (ret & VM_FAULT_ERROR)
> copied = 0;
> /*
> @@ -1677,7 +1683,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct
> vm_fault *vmf, pfn_t *pfnp,
> pgoff_t max_pgoff;
> void *entry;
> loff_t pos;
> - int error;
> + int error, copied = PMD_SIZE;
>
> /*
> * Check whether offset isn't beyond end of file now. Caller is @@ -1736,12
> +1742,15 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf,
> pfn_t *pfnp,
> ret = dax_fault_actor(vmf, pfnp, &xas, &entry, true, flags,
> &iomap, &srcmap);
>
> + if (ret == VM_FAULT_FALLBACK)
> + copied = 0;
> + if (ops->iomap_post_actor) {
> + ops->iomap_post_actor(inode, pos, PMD_SIZE, copied, flags,
> + &iomap, &srcmap);
> + }
> +
> finish_iomap:
> if (ops->iomap_end) {
> - int copied = PMD_SIZE;
> -
> - if (ret == VM_FAULT_FALLBACK)
> - copied = 0;
> /*
> * The fault is done by now and there's no way back (other
> * thread may be already happily using PMD we have installed).
> diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c index
> 0493da5286ad..26a54ded184f 100644
> --- a/fs/iomap/apply.c
> +++ b/fs/iomap/apply.c
> @@ -84,6 +84,10 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length,
> unsigned flags,
> written = actor(inode, pos, length, data, &iomap,
> srcmap.type != IOMAP_HOLE ? &srcmap : &iomap);
>
> + if (ops->iomap_post_actor) {
> + written = ops->iomap_post_actor(inode, pos, length, written,
> + flags, &iomap, &srcmap);
> + }
> out:
> /*
> * Now the data has been copied, commit the range we've copied. This
> diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index
> a5e9d7d34023..2a36dc93ff27 100644
> --- a/fs/xfs/xfs_bmap_util.c
> +++ b/fs/xfs/xfs_bmap_util.c
> @@ -965,8 +965,7 @@ xfs_free_file_space(
> return 0;
> if (offset + len > XFS_ISIZE(ip))
> len = XFS_ISIZE(ip) - offset;
> - error = iomap_zero_range(VFS_I(ip), offset, len, NULL,
> - &xfs_buffered_write_iomap_ops);
> + error = xfs_iomap_zero_range(ip, offset, len, NULL);
> if (error)
> return error;
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 396ef36dcd0a..89406ec6741b
> 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -684,11 +684,12 @@ xfs_file_dax_write(
> pos = iocb->ki_pos;
>
> trace_xfs_file_dax_write(iocb, from);
> - ret = dax_iomap_rw(iocb, from, &xfs_direct_write_iomap_ops);
> + ret = dax_iomap_rw(iocb, from, &xfs_dax_write_iomap_ops);
> if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
> i_size_write(inode, iocb->ki_pos);
> error = xfs_setfilesize(ip, pos, ret);
> }
> +
> out:
> if (iolock)
> xfs_iunlock(ip, iolock);
> @@ -1309,7 +1310,7 @@ __xfs_filemap_fault(
>
> ret = dax_iomap_fault(vmf, pe_size, &pfn, NULL,
> (write_fault && !vmf->cow_page) ?
> - &xfs_direct_write_iomap_ops :
> + &xfs_dax_write_iomap_ops :
> &xfs_read_iomap_ops);
> if (ret & VM_FAULT_NEEDDSYNC)
> ret = dax_finish_sync_fault(vmf, pe_size, pfn); diff --git
> a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index d154f42e2dc6..2f322e2f8544
> 100644
> --- a/fs/xfs/xfs_iomap.c
> +++ b/fs/xfs/xfs_iomap.c
> @@ -761,7 +761,8 @@ xfs_direct_write_iomap_begin(
>
> /* may drop and re-acquire the ilock */
> error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
> - &lockmode, flags & IOMAP_DIRECT);
> + &lockmode,
> + (flags & IOMAP_DIRECT) || IS_DAX(inode));
> if (error)
> goto out_unlock;
> if (shared)
> @@ -854,6 +855,36 @@ const struct iomap_ops xfs_direct_write_iomap_ops =
> {
> .iomap_begin = xfs_direct_write_iomap_begin,
> };
>
> +static int
> +xfs_dax_write_iomap_post_actor(
> + struct inode *inode,
> + loff_t pos,
> + loff_t length,
> + ssize_t written,
> + unsigned int flags,
> + struct iomap *iomap,
> + struct iomap *srcmap)
> +{
> + int error = 0;
> + struct xfs_inode *ip = XFS_I(inode);
> + bool cow = xfs_is_cow_inode(ip);
> +
> + if (written <= 0) {
> + if (cow)
> + xfs_reflink_cancel_cow_range(ip, pos, length, true);
> + return written;
> + }
> +
> + if (cow)
> + error = xfs_reflink_end_cow(ip, pos, written);
> + return error ?: written;
> +}
> +
> +const struct iomap_ops xfs_dax_write_iomap_ops = {
> + .iomap_begin = xfs_direct_write_iomap_begin,
> + .iomap_post_actor = xfs_dax_write_iomap_post_actor,
> +};
> +
> static int
> xfs_buffered_write_iomap_begin(
> struct inode *inode,
> diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h index
> 7d3703556d0e..fbacf638ab21 100644
> --- a/fs/xfs/xfs_iomap.h
> +++ b/fs/xfs/xfs_iomap.h
> @@ -42,8 +42,32 @@ xfs_aligned_fsb_count(
>
> extern const struct iomap_ops xfs_buffered_write_iomap_ops; extern const
> struct iomap_ops xfs_direct_write_iomap_ops;
> +extern const struct iomap_ops xfs_dax_write_iomap_ops;
> extern const struct iomap_ops xfs_read_iomap_ops; extern const struct
> iomap_ops xfs_seek_iomap_ops; extern const struct iomap_ops
> xfs_xattr_iomap_ops;
>
> +static inline int
> +xfs_iomap_zero_range(
> + struct xfs_inode *ip,
> + loff_t offset,
> + loff_t len,
> + bool *did_zero)
> +{
> + return iomap_zero_range(VFS_I(ip), offset, len, did_zero,
> + IS_DAX(VFS_I(ip)) ? &xfs_dax_write_iomap_ops
> + : &xfs_buffered_write_iomap_ops); }
> +
> +static inline int
> +xfs_iomap_truncate_page(
> + struct xfs_inode *ip,
> + loff_t pos,
> + bool *did_zero)
> +{
> + return iomap_truncate_page(VFS_I(ip), pos, did_zero,
> + IS_DAX(VFS_I(ip)) ? &xfs_dax_write_iomap_ops
> + : &xfs_buffered_write_iomap_ops); }
> +
> #endif /* __XFS_IOMAP_H__*/
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index
> dfe24b7f26e5..6d936c3e1a6e 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -911,8 +911,8 @@ xfs_setattr_size(
> */
> if (newsize > oldsize) {
> trace_xfs_zero_eof(ip, oldsize, newsize - oldsize);
> - error = iomap_zero_range(inode, oldsize, newsize - oldsize,
> - &did_zeroing, &xfs_buffered_write_iomap_ops);
> + error = xfs_iomap_zero_range(ip, oldsize, newsize - oldsize,
> + &did_zeroing);
> } else {
> /*
> * iomap won't detect a dirty page over an unwritten block (or a @@
> -924,8 +924,7 @@ xfs_setattr_size(
> newsize);
> if (error)
> return error;
> - error = iomap_truncate_page(inode, newsize, &did_zeroing,
> - &xfs_buffered_write_iomap_ops);
> + error = xfs_iomap_truncate_page(ip, newsize, &did_zeroing);
> }
>
> if (error)
> diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index
> d25434f93235..9a780948dbd0 100644
> --- a/fs/xfs/xfs_reflink.c
> +++ b/fs/xfs/xfs_reflink.c
> @@ -1266,8 +1266,7 @@ xfs_reflink_zero_posteof(
> return 0;
>
> trace_xfs_zero_eof(ip, isize, pos - isize);
> - return iomap_zero_range(VFS_I(ip), isize, pos - isize, NULL,
> - &xfs_buffered_write_iomap_ops);
> + return xfs_iomap_zero_range(ip, isize, pos - isize, NULL);
> }
>
> /*
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h index
> 95562f863ad0..58f2e1c78018 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -135,6 +135,14 @@ struct iomap_ops {
> unsigned flags, struct iomap *iomap,
> struct iomap *srcmap);
>
> + /*
> + * Handle the error code from actor(). Do the finishing jobs for extra
> + * operations, such as CoW, according to whether written is negative.
> + */
> + int (*iomap_post_actor)(struct inode *inode, loff_t pos, loff_t length,
> + ssize_t written, unsigned flags, struct iomap *iomap,
> + struct iomap *srcmap);
> +
> /*
> * Commit and/or unreserve space previous allocated using iomap_begin.
> * Written indicates the length of the successful write operation which
> --
> 2.31.1
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