[Cluster-devel] [PATCH 29/30] fsdax: switch the fault handlers to use iomap_iter
Christoph Hellwig
hch at lst.de
Mon Aug 9 06:12:43 UTC 2021
Avoid the open coded calls to ->iomap_begin and ->iomap_end and call
iomap_iter instead.
Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Darrick J. Wong <djwong at kernel.org>
---
fs/dax.c | 193 +++++++++++++++++++++----------------------------------
1 file changed, 75 insertions(+), 118 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 6d0c6d28be83b1..118c9e2923f5f8 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1010,7 +1010,7 @@ static sector_t dax_iomap_sector(const struct iomap *iomap, loff_t pos)
return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
}
-static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
+static int dax_iomap_pfn(const struct iomap *iomap, loff_t pos, size_t size,
pfn_t *pfnp)
{
const sector_t sector = dax_iomap_sector(iomap, pos);
@@ -1068,7 +1068,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas,
#ifdef CONFIG_FS_DAX_PMD
static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
- struct iomap *iomap, void **entry)
+ const struct iomap *iomap, void **entry)
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
unsigned long pmd_addr = vmf->address & PMD_MASK;
@@ -1120,7 +1120,7 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
}
#else
static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
- struct iomap *iomap, void **entry)
+ const struct iomap *iomap, void **entry)
{
return VM_FAULT_FALLBACK;
}
@@ -1309,7 +1309,7 @@ static vm_fault_t dax_fault_return(int error)
* 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)
+ struct vm_area_struct *vma, const struct iomap *iomap)
{
return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC)
&& (iomap->flags & IOMAP_F_DIRTY);
@@ -1329,22 +1329,22 @@ static vm_fault_t dax_fault_synchronous_pfnp(pfn_t *pfnp, pfn_t pfn)
return VM_FAULT_NEEDDSYNC;
}
-static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap,
- loff_t pos)
+static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf,
+ const struct iomap_iter *iter)
{
- sector_t sector = dax_iomap_sector(iomap, pos);
+ sector_t sector = dax_iomap_sector(&iter->iomap, iter->pos);
unsigned long vaddr = vmf->address;
vm_fault_t ret;
int error = 0;
- switch (iomap->type) {
+ switch (iter->iomap.type) {
case IOMAP_HOLE:
case IOMAP_UNWRITTEN:
clear_user_highpage(vmf->cow_page, vaddr);
break;
case IOMAP_MAPPED:
- error = copy_cow_page_dax(iomap->bdev, iomap->dax_dev, sector,
- vmf->cow_page, vaddr);
+ error = copy_cow_page_dax(iter->iomap.bdev, iter->iomap.dax_dev,
+ sector, vmf->cow_page, vaddr);
break;
default:
WARN_ON_ONCE(1);
@@ -1363,29 +1363,31 @@ static vm_fault_t dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap,
}
/**
- * dax_fault_actor - Common actor to handle pfn insertion in PTE/PMD fault.
+ * dax_fault_iter - Common actor to handle pfn insertion in PTE/PMD fault.
* @vmf: vm fault instance
+ * @iter: iomap iter
* @pfnp: pfn to be returned
* @xas: the dax mapping tree of a file
* @entry: an unlocked dax entry to be inserted
* @pmd: distinguish whether it is a pmd fault
- * @flags: iomap flags
- * @iomap: from iomap_begin()
- * @srcmap: from iomap_begin(), not equal to iomap if it is a CoW
*/
-static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp,
- struct xa_state *xas, void **entry, bool pmd,
- unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
+static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
+ const struct iomap_iter *iter, pfn_t *pfnp,
+ struct xa_state *xas, void **entry, bool pmd)
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+ const struct iomap *iomap = &iter->iomap;
size_t size = pmd ? PMD_SIZE : PAGE_SIZE;
loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT;
bool write = vmf->flags & FAULT_FLAG_WRITE;
- bool sync = dax_fault_is_synchronous(flags, vmf->vma, iomap);
+ bool sync = dax_fault_is_synchronous(iter->flags, vmf->vma, iomap);
unsigned long entry_flags = pmd ? DAX_PMD : 0;
int err = 0;
pfn_t pfn;
+ if (!pmd && vmf->cow_page)
+ return dax_fault_cow_page(vmf, iter);
+
/* if we are reading UNWRITTEN and HOLE, return a hole. */
if (!write &&
(iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) {
@@ -1399,7 +1401,7 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp,
return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS;
}
- err = dax_iomap_pfn(iomap, pos, size, &pfn);
+ err = dax_iomap_pfn(&iter->iomap, pos, size, &pfn);
if (err)
return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err);
@@ -1422,32 +1424,31 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp,
static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
int *iomap_errp, const struct iomap_ops *ops)
{
- struct vm_area_struct *vma = vmf->vma;
- struct address_space *mapping = vma->vm_file->f_mapping;
+ struct address_space *mapping = vmf->vma->vm_file->f_mapping;
XA_STATE(xas, &mapping->i_pages, vmf->pgoff);
- struct inode *inode = mapping->host;
- loff_t pos = (loff_t)vmf->pgoff << PAGE_SHIFT;
- struct iomap iomap = { .type = IOMAP_HOLE };
- struct iomap srcmap = { .type = IOMAP_HOLE };
- unsigned flags = IOMAP_FAULT;
- int error;
- bool write = vmf->flags & FAULT_FLAG_WRITE;
- vm_fault_t ret = 0, major = 0;
+ struct iomap_iter iter = {
+ .inode = mapping->host,
+ .pos = (loff_t)vmf->pgoff << PAGE_SHIFT,
+ .len = PAGE_SIZE,
+ .flags = IOMAP_FAULT,
+ };
+ vm_fault_t ret = 0;
void *entry;
+ int error;
- trace_dax_pte_fault(inode, vmf, ret);
+ trace_dax_pte_fault(iter.inode, vmf, ret);
/*
* Check whether offset isn't beyond end of file now. Caller is supposed
* to hold locks serializing us with truncate / punch hole so this is
* a reliable test.
*/
- if (pos >= i_size_read(inode)) {
+ if (iter.pos >= i_size_read(iter.inode)) {
ret = VM_FAULT_SIGBUS;
goto out;
}
- if (write && !vmf->cow_page)
- flags |= IOMAP_WRITE;
+ if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
+ iter.flags |= IOMAP_WRITE;
entry = grab_mapping_entry(&xas, mapping, 0);
if (xa_is_internal(entry)) {
@@ -1466,59 +1467,34 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto unlock_entry;
}
- /*
- * Note that we don't bother to use iomap_iter here: DAX required
- * the file system block size to be equal the page size, which means
- * that we never have to deal with more than a single extent here.
- */
- error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap, &srcmap);
- if (iomap_errp)
- *iomap_errp = error;
- if (error) {
- ret = dax_fault_return(error);
- goto unlock_entry;
- }
- if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
- ret = VM_FAULT_SIGBUS; /* fs corruption? */
- goto finish_iomap;
- }
-
- if (vmf->cow_page) {
- ret = dax_fault_cow_page(vmf, &iomap, pos);
- goto finish_iomap;
- }
+ while ((error = iomap_iter(&iter, ops)) > 0) {
+ if (WARN_ON_ONCE(iomap_length(&iter) < PAGE_SIZE)) {
+ iter.processed = -EIO; /* fs corruption? */
+ continue;
+ }
- ret = dax_fault_actor(vmf, pfnp, &xas, &entry, false, flags,
- &iomap, &srcmap);
- if (ret == VM_FAULT_SIGBUS)
- goto finish_iomap;
+ ret = dax_fault_iter(vmf, &iter, pfnp, &xas, &entry, false);
+ if (ret != VM_FAULT_SIGBUS &&
+ (iter.iomap.flags & IOMAP_F_NEW)) {
+ count_vm_event(PGMAJFAULT);
+ count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
+ ret |= VM_FAULT_MAJOR;
+ }
- /* read/write MAPPED, CoW UNWRITTEN */
- if (iomap.flags & IOMAP_F_NEW) {
- count_vm_event(PGMAJFAULT);
- count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
- major = VM_FAULT_MAJOR;
+ if (!(ret & VM_FAULT_ERROR))
+ iter.processed = PAGE_SIZE;
}
-finish_iomap:
- if (ops->iomap_end) {
- int copied = PAGE_SIZE;
+ if (iomap_errp)
+ *iomap_errp = error;
+ if (!ret && error)
+ ret = dax_fault_return(error);
- if (ret & VM_FAULT_ERROR)
- copied = 0;
- /*
- * The fault is done by now and there's no way back (other
- * thread may be already happily using PTE we have installed).
- * Just ignore error from ->iomap_end since we cannot do much
- * with it.
- */
- ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
- }
unlock_entry:
dax_unlock_entry(&xas, entry);
out:
- trace_dax_pte_fault_done(inode, vmf, ret);
- return ret | major;
+ trace_dax_pte_fault_done(iter.inode, vmf, ret);
+ return ret;
}
#ifdef CONFIG_FS_DAX_PMD
@@ -1558,28 +1534,29 @@ static bool dax_fault_check_fallback(struct vm_fault *vmf, struct xa_state *xas,
static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
const struct iomap_ops *ops)
{
- struct vm_area_struct *vma = vmf->vma;
- struct address_space *mapping = vma->vm_file->f_mapping;
+ struct address_space *mapping = vmf->vma->vm_file->f_mapping;
XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER);
- bool write = vmf->flags & FAULT_FLAG_WRITE;
- unsigned int flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
- struct inode *inode = mapping->host;
+ struct iomap_iter iter = {
+ .inode = mapping->host,
+ .len = PMD_SIZE,
+ .flags = IOMAP_FAULT,
+ };
vm_fault_t ret = VM_FAULT_FALLBACK;
- struct iomap iomap = { .type = IOMAP_HOLE };
- struct iomap srcmap = { .type = IOMAP_HOLE };
pgoff_t max_pgoff;
void *entry;
- loff_t pos;
int error;
+ if (vmf->flags & FAULT_FLAG_WRITE)
+ iter.flags |= IOMAP_WRITE;
+
/*
* Check whether offset isn't beyond end of file now. Caller is
* supposed to hold locks serializing us with truncate / punch hole so
* this is a reliable test.
*/
- max_pgoff = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
+ max_pgoff = DIV_ROUND_UP(i_size_read(iter.inode), PAGE_SIZE);
- trace_dax_pmd_fault(inode, vmf, max_pgoff, 0);
+ trace_dax_pmd_fault(iter.inode, vmf, max_pgoff, 0);
if (xas.xa_index >= max_pgoff) {
ret = VM_FAULT_SIGBUS;
@@ -1613,45 +1590,25 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto unlock_entry;
}
- /*
- * Note that we don't use iomap_iter here. We aren't doing I/O, only
- * setting up a mapping, so really we're using iomap_begin() as a way
- * to look up our filesystem block.
- */
- pos = (loff_t)xas.xa_index << PAGE_SHIFT;
- error = ops->iomap_begin(inode, pos, PMD_SIZE, flags, &iomap, &srcmap);
- if (error)
- goto unlock_entry;
-
- if (iomap.offset + iomap.length < pos + PMD_SIZE)
- goto finish_iomap;
+ iter.pos = (loff_t)xas.xa_index << PAGE_SHIFT;
+ while ((error = iomap_iter(&iter, ops)) > 0) {
+ if (iomap_length(&iter) < PMD_SIZE)
+ continue; /* actually breaks out of the loop */
- ret = dax_fault_actor(vmf, pfnp, &xas, &entry, true, 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).
- * Just ignore error from ->iomap_end since we cannot do much
- * with it.
- */
- ops->iomap_end(inode, pos, PMD_SIZE, copied, flags, &iomap);
+ ret = dax_fault_iter(vmf, &iter, pfnp, &xas, &entry, true);
+ if (ret != VM_FAULT_FALLBACK)
+ iter.processed = PMD_SIZE;
}
+
unlock_entry:
dax_unlock_entry(&xas, entry);
fallback:
if (ret == VM_FAULT_FALLBACK) {
- split_huge_pmd(vma, vmf->pmd, vmf->address);
+ split_huge_pmd(vmf->vma, vmf->pmd, vmf->address);
count_vm_event(THP_FAULT_FALLBACK);
}
out:
- trace_dax_pmd_fault_done(inode, vmf, max_pgoff, ret);
+ trace_dax_pmd_fault_done(iter.inode, vmf, max_pgoff, ret);
return ret;
}
#else
--
2.30.2
More information about the Cluster-devel
mailing list