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fs/dax.c: use new return type vm_fault_t

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Use new return type vm_fault_t for fault handler.  For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno.  Once all instances are converted, vm_fault_t will become a
distinct type.

commit 1c8f422059 ("mm: change return type to vm_fault_t")

There was an existing bug inside dax_load_hole() if vm_insert_mixed had
failed to allocate a page table, we'd return VM_FAULT_NOPAGE instead of
VM_FAULT_OOM.  With new vmf_insert_mixed() this issue is addressed.

vm_insert_mixed_mkwrite has inefficiency when it returns an error value,
driver has to convert it to vm_fault_t type.  With new
vmf_insert_mixed_mkwrite() this limitation will be addressed.

Link: http://lkml.kernel.org/r/20180510181121.GA15239@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Souptick Joarder 2018-06-07 17:04:29 -07:00 committed by Linus Torvalds
parent 3036bc4536
commit ab77dab462
4 changed files with 58 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
fs/dax.c
View File

@ -905,12 +905,12 @@ out:
* If this page is ever written to we will re-fault and change the mapping to
* point to real DAX storage instead.
*/
static int dax_load_hole(struct address_space *mapping, void *entry,
static vm_fault_t dax_load_hole(struct address_space *mapping, void *entry,
struct vm_fault *vmf)
{
struct inode *inode = mapping->host;
unsigned long vaddr = vmf->address;
int ret = VM_FAULT_NOPAGE;
vm_fault_t ret = VM_FAULT_NOPAGE;
struct page *zero_page;
void *entry2;
pfn_t pfn;
@ -929,7 +929,7 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
goto out;
}
vm_insert_mixed(vmf->vma, vaddr, pfn);
ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
out:
trace_dax_load_hole(inode, vmf, ret);
return ret;
@ -1112,7 +1112,7 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
}
EXPORT_SYMBOL_GPL(dax_iomap_rw);
static int dax_fault_return(int error)
static vm_fault_t dax_fault_return(int error)
{
if (error == 0)
return VM_FAULT_NOPAGE;
@ -1132,7 +1132,7 @@ static bool dax_fault_is_synchronous(unsigned long flags,
&& (iomap->flags & IOMAP_F_DIRTY);
}
static int dax_iomap_pte_fault(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;
@ -1145,18 +1145,18 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
int error, major = 0;
bool write = vmf->flags & FAULT_FLAG_WRITE;
bool sync;
int vmf_ret = 0;
vm_fault_t ret = 0;
void *entry;
pfn_t pfn;
trace_dax_pte_fault(inode, vmf, vmf_ret);
trace_dax_pte_fault(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)) {
vmf_ret = VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
goto out;
}
@ -1165,7 +1165,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
if (IS_ERR(entry)) {
vmf_ret = dax_fault_return(PTR_ERR(entry));
ret = dax_fault_return(PTR_ERR(entry));
goto out;
}
@ -1176,7 +1176,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
* retried.
*/
if (pmd_trans_huge(*vmf->pmd) || pmd_devmap(*vmf->pmd)) {
vmf_ret = VM_FAULT_NOPAGE;
ret = VM_FAULT_NOPAGE;
goto unlock_entry;
}
@ -1189,7 +1189,7 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
if (iomap_errp)
*iomap_errp = error;
if (error) {
vmf_ret = dax_fault_return(error);
ret = dax_fault_return(error);
goto unlock_entry;
}
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
@ -1219,9 +1219,9 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto error_finish_iomap;
__SetPageUptodate(vmf->cow_page);
vmf_ret = finish_fault(vmf);
if (!vmf_ret)
vmf_ret = VM_FAULT_DONE_COW;
ret = finish_fault(vmf);
if (!ret)
ret = VM_FAULT_DONE_COW;
goto finish_iomap;
}
@ -1257,23 +1257,20 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto error_finish_iomap;
}
*pfnp = pfn;
vmf_ret = VM_FAULT_NEEDDSYNC | major;
ret = VM_FAULT_NEEDDSYNC | major;
goto finish_iomap;
}
trace_dax_insert_mapping(inode, vmf, entry);
if (write)
error = vm_insert_mixed_mkwrite(vma, vaddr, pfn);
ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn);
else
error = vm_insert_mixed(vma, vaddr, pfn);
ret = vmf_insert_mixed(vma, vaddr, pfn);
/* -EBUSY is fine, somebody else faulted on the same PTE */
if (error == -EBUSY)
error = 0;
break;
goto finish_iomap;
case IOMAP_UNWRITTEN:
case IOMAP_HOLE:
if (!write) {
vmf_ret = dax_load_hole(mapping, entry, vmf);
ret = dax_load_hole(mapping, entry, vmf);
goto finish_iomap;
}
/*FALLTHRU*/
@ -1284,12 +1281,12 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
}
error_finish_iomap:
vmf_ret = dax_fault_return(error) | major;
ret = dax_fault_return(error);
finish_iomap:
if (ops->iomap_end) {
int copied = PAGE_SIZE;
if (vmf_ret & VM_FAULT_ERROR)
if (ret & VM_FAULT_ERROR)
copied = 0;
/*
* The fault is done by now and there's no way back (other
@ -1302,12 +1299,12 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
unlock_entry:
put_locked_mapping_entry(mapping, vmf->pgoff);
out:
trace_dax_pte_fault_done(inode, vmf, vmf_ret);
return vmf_ret;
trace_dax_pte_fault_done(inode, vmf, ret);
return ret | major;
}
#ifdef CONFIG_FS_DAX_PMD
static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
static vm_fault_t dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap,
void *entry)
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
@ -1348,7 +1345,7 @@ fallback:
return VM_FAULT_FALLBACK;
}
static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
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;
@ -1358,7 +1355,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
bool sync;
unsigned int iomap_flags = (write ? IOMAP_WRITE : 0) | IOMAP_FAULT;
struct inode *inode = mapping->host;
int result = VM_FAULT_FALLBACK;
vm_fault_t result = VM_FAULT_FALLBACK;
struct iomap iomap = { 0 };
pgoff_t max_pgoff, pgoff;
void *entry;
@ -1509,7 +1506,7 @@ out:
return result;
}
#else
static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
const struct iomap_ops *ops)
{
return VM_FAULT_FALLBACK;
@ -1529,7 +1526,7 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
* has done all the necessary locking for page fault to proceed
* successfully.
*/
int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
vm_fault_t dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
pfn_t *pfnp, int *iomap_errp, const struct iomap_ops *ops)
{
switch (pe_size) {
@ -1553,14 +1550,14 @@ EXPORT_SYMBOL_GPL(dax_iomap_fault);
* DAX file. It takes care of marking corresponding radix tree entry as dirty
* as well.
*/
static int dax_insert_pfn_mkwrite(struct vm_fault *vmf,
static vm_fault_t dax_insert_pfn_mkwrite(struct vm_fault *vmf,
enum page_entry_size pe_size,
pfn_t pfn)
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
void *entry, **slot;
pgoff_t index = vmf->pgoff;
int vmf_ret, error;
vm_fault_t ret;
xa_lock_irq(&mapping->i_pages);
entry = get_unlocked_mapping_entry(mapping, index, &slot);
@ -1579,21 +1576,20 @@ static int dax_insert_pfn_mkwrite(struct vm_fault *vmf,
xa_unlock_irq(&mapping->i_pages);
switch (pe_size) {
case PE_SIZE_PTE:
error = vm_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
vmf_ret = dax_fault_return(error);
ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
break;
#ifdef CONFIG_FS_DAX_PMD
case PE_SIZE_PMD:
vmf_ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
pfn, true);
break;
#endif
default:
vmf_ret = VM_FAULT_FALLBACK;
ret = VM_FAULT_FALLBACK;
}
put_locked_mapping_entry(mapping, index);
trace_dax_insert_pfn_mkwrite(mapping->host, vmf, vmf_ret);
return vmf_ret;
trace_dax_insert_pfn_mkwrite(mapping->host, vmf, ret);
return ret;
}
/**
@ -1606,8 +1602,8 @@ static int dax_insert_pfn_mkwrite(struct vm_fault *vmf,
* stored persistently on the media and handles inserting of appropriate page
* table entry.
*/
int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
pfn_t pfn)
vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
enum page_entry_size pe_size, pfn_t pfn)
{
int err;
loff_t start = ((loff_t)vmf->pgoff) << PAGE_SHIFT;

4
include/linux/dax.h
View File

@ -125,8 +125,8 @@ ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops);
int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
pfn_t *pfnp, int *errp, const struct iomap_ops *ops);
int dax_finish_sync_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
pfn_t pfn);
vm_fault_t dax_finish_sync_fault(struct vm_fault *vmf,
enum page_entry_size pe_size, pfn_t pfn);
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index);

4
include/linux/mm.h
View File

@ -2431,8 +2431,8 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, pgprot_t pgprot);
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
static inline vm_fault_t vmf_insert_page(struct vm_area_struct *vma,

21
mm/memory.c
View File

@ -1955,12 +1955,25 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
}
EXPORT_SYMBOL(vm_insert_mixed);
int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn)
/*
* If the insertion of PTE failed because someone else already added a
* different entry in the mean time, we treat that as success as we assume
* the same entry was actually inserted.
*/
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn)
{
return __vm_insert_mixed(vma, addr, pfn, true);
int err;
err = __vm_insert_mixed(vma, addr, pfn, true);
if (err == -ENOMEM)
return VM_FAULT_OOM;
if (err < 0 && err != -EBUSY)
return VM_FAULT_SIGBUS;
return VM_FAULT_NOPAGE;
}
EXPORT_SYMBOL(vm_insert_mixed_mkwrite);
EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
/*
* maps a range of physical memory into the requested pages. the old