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Commit ab77dab4 authored by Souptick Joarder's avatar Souptick Joarder Committed by Linus Torvalds
Browse files

fs/dax.c: use new return type vm_fault_t 

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 1c8f4220 ("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: default avatarSouptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: default avatarRoss 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3036bc45

fs/dax.c

+37 −41
Original line number Diff line number Diff line
@@ -905,12 +905,12 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, 
 * 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 @@ static int dax_pmd_load_hole(struct vm_fault *vmf, struct iomap *iomap, 
	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 @@ static int dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, 
	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;

include/linux/dax.h

+2 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/mm.h

+2 −2
Original line number Diff line number Diff line
@@ -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,

mm/memory.c

+17 −4
Original line number Diff line number Diff line
@@ -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