From: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
To: <linux-kernel@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
<linux-nvdimm@lists.01.org>
Cc: <linux-mm@kvack.org>, <linux-fsdevel@vger.kernel.org>,
<darrick.wong@oracle.com>, <dan.j.williams@intel.com>,
<david@fromorbit.com>, <hch@lst.de>, <rgoldwyn@suse.de>,
<qi.fuli@fujitsu.com>, <y-goto@fujitsu.com>
Subject: [RFC PATCH 4/8] fsdax: copy data before write
Date: Fri, 7 Aug 2020 21:13:32 +0800 [thread overview]
Message-ID: <20200807131336.318774-5-ruansy.fnst@cn.fujitsu.com> (raw)
In-Reply-To: <20200807131336.318774-1-ruansy.fnst@cn.fujitsu.com>
Add dax_copy_edges() into each dax actor functions to perform CoW.
Signed-off-by: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
---
fs/dax.c | 39 +++++++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 308678c58d4d..65553e3f7602 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1208,7 +1208,8 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
return iov_iter_zero(min(length, end - pos), iter);
}
- if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
+ if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED &&
+ !(iomap->flags & IOMAP_F_SHARED)))
return -EIO;
/*
@@ -1247,6 +1248,12 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
break;
}
+ if (iomap != srcmap) {
+ ret = dax_copy_edges(pos, length, srcmap, kaddr, false);
+ if (ret)
+ break;
+ }
+
map_len = PFN_PHYS(map_len);
kaddr += offset;
map_len -= offset;
@@ -1358,6 +1365,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
vm_fault_t ret = 0;
void *entry;
pfn_t pfn;
+ void *kaddr;
trace_dax_pte_fault(inode, vmf, ret);
/*
@@ -1439,19 +1447,27 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
switch (iomap.type) {
case IOMAP_MAPPED:
+cow:
if (iomap.flags & IOMAP_F_NEW) {
count_vm_event(PGMAJFAULT);
count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
major = VM_FAULT_MAJOR;
}
error = dax_iomap_direct_access(&iomap, pos, PAGE_SIZE, &pfn,
- NULL);
+ &kaddr);
if (error < 0)
goto error_finish_iomap;
entry = dax_insert_entry(&xas, mapping, vmf, iomap.addr, entry,
pfn, 0, write && !sync);
+ if (srcmap.type != IOMAP_HOLE) {
+ error = dax_copy_edges(pos, PAGE_SIZE, &srcmap, kaddr,
+ false);
+ if (error)
+ goto error_finish_iomap;
+ }
+
/*
* If we are doing synchronous page fault and inode needs fsync,
* we can insert PTE into page tables only after that happens.
@@ -1475,12 +1491,15 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto finish_iomap;
case IOMAP_UNWRITTEN:
+ if (write && iomap.flags & IOMAP_F_SHARED)
+ goto cow;
+ fallthrough;
case IOMAP_HOLE:
if (!write) {
ret = dax_load_hole(&xas, mapping, &entry, vmf);
goto finish_iomap;
}
- /*FALLTHRU*/
+ fallthrough;
default:
WARN_ON_ONCE(1);
error = -EIO;
@@ -1582,6 +1601,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
loff_t pos;
int error;
pfn_t pfn;
+ void *kaddr;
/*
* Check whether offset isn't beyond end of file now. Caller is
@@ -1663,14 +1683,22 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
switch (iomap.type) {
case IOMAP_MAPPED:
+cow:
error = dax_iomap_direct_access(&iomap, pos, PMD_SIZE, &pfn,
- NULL);
+ &kaddr);
if (error < 0)
goto finish_iomap;
entry = dax_insert_entry(&xas, mapping, vmf, iomap.addr, entry,
pfn, DAX_PMD, write && !sync);
+ if (srcmap.type != IOMAP_HOLE) {
+ error = dax_copy_edges(pos, PMD_SIZE, &srcmap, kaddr,
+ true);
+ if (error)
+ goto unlock_entry;
+ }
+
/*
* If we are doing synchronous page fault and inode needs fsync,
* we can insert PMD into page tables only after that happens.
@@ -1689,6 +1717,9 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
result = vmf_insert_pfn_pmd(vmf, pfn, write);
break;
case IOMAP_UNWRITTEN:
+ if (write && iomap.flags & IOMAP_F_SHARED)
+ goto cow;
+ fallthrough;
case IOMAP_HOLE:
if (WARN_ON_ONCE(write))
break;
--
2.27.0
next prev parent reply other threads:[~2020-08-07 13:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-07 13:13 [RFC PATCH 0/8] fsdax: introduce FS query interface to support reflink Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 1/8] fs: introduce get_shared_files() for dax&reflink Shiyang Ruan
2020-08-07 16:15 ` Darrick J. Wong
2020-08-10 8:07 ` Ruan Shiyang
2020-08-07 13:13 ` [RFC PATCH 2/8] fsdax, mm: track files sharing dax page for memory-failure Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 3/8] fsdax: introduce dax_copy_edges() for COW Shiyang Ruan
2020-08-07 13:13 ` Shiyang Ruan [this message]
2020-08-07 13:13 ` [RFC PATCH 5/8] fsdax: replace mmap entry in case of CoW Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 6/8] fsdax: dedup file range to use a compare function Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 7/8] fs/xfs: handle CoW for fsdax write() path Shiyang Ruan
2020-08-07 13:13 ` [RFC PATCH 8/8] fs/xfs: support dedupe for fsdax Shiyang Ruan
2020-08-07 13:38 ` [RFC PATCH 0/8] fsdax: introduce FS query interface to support reflink Matthew Wilcox
2020-08-10 8:15 ` Ruan Shiyang
2020-08-10 11:16 ` Matthew Wilcox
2020-08-10 21:10 ` Dave Chinner
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