linux-ext4 - [PATCH 10/13] mm: Wire up MAP

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Date:   Thu, 17 Aug 2017 18:08:12 +0200
From:   Jan Kara <jack@...e.cz>
To:     <linux-fsdevel@...r.kernel.org>
Cc:     linux-nvdimm@...ts.01.org, Andy Lutomirski <luto@...nel.org>,
        <linux-ext4@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Boaz Harrosh <boazh@...app.com>, Jan Kara <jack@...e.cz>
Subject: [PATCH 10/13] mm: Wire up MAP_SYNC

Pretty crude for now...

Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/file.c                  | 2 ++
 include/linux/mm.h              | 1 +
 include/linux/mman.h            | 3 ++-
 include/uapi/asm-generic/mman.h | 1 +
 mm/mmap.c                       | 5 +++++
 5 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index f84bb29e941e..850037e140d7 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -340,6 +340,8 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 		vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 	} else {
 		vma->vm_ops = &ext4_file_vm_ops;
+		if (vma->vm_flags & VM_SYNC)
+			return -EOPNOTSUPP;
 	}
 	return 0;
 }
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fa036093e76c..d0fb385414a4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -188,6 +188,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_ACCOUNT	0x00100000	/* Is a VM accounted object */
 #define VM_NORESERVE	0x00200000	/* should the VM suppress accounting */
 #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
+#define VM_SYNC		0x00800000	/* Synchronous page faults */
 #define VM_ARCH_1	0x01000000	/* Architecture-specific flag */
 #define VM_ARCH_2	0x02000000
 #define VM_DONTDUMP	0x04000000	/* Do not include in the core dump */
diff --git a/include/linux/mman.h b/include/linux/mman.h
index c8367041fafd..c38279b651e5 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -86,7 +86,8 @@ calc_vm_flag_bits(unsigned long flags)
 {
 	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
 	       _calc_vm_trans(flags, MAP_DENYWRITE,  VM_DENYWRITE ) |
-	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    );
+	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
+	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      );
 }
 
 unsigned long vm_commit_limit(void);
diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h
index 7162cd4cca73..00e55627d2df 100644
--- a/include/uapi/asm-generic/mman.h
+++ b/include/uapi/asm-generic/mman.h
@@ -12,6 +12,7 @@
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
 #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
 #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
+#define MAP_SYNC	0x80000		/* perform synchronous page faults for the mapping */
 
 /* Bits [26:31] are reserved, see mman-common.h for MAP_HUGETLB usage */
 
diff --git a/mm/mmap.c b/mm/mmap.c
index f19efcf75418..18453c04b09f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1423,12 +1423,17 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 				return -ENODEV;
 			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
 				return -EINVAL;
+			if (!(vm_flags & VM_SHARED) && (vm_flags & VM_SYNC))
+				return -EINVAL;
 			break;
 
 		default:
 			return -EINVAL;
 		}
 	} else {
+		if (vm_flags & VM_SYNC)
+			return -EINVAL;
+
 		switch (flags & MAP_TYPE) {
 		case MAP_SHARED:
 			if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
-- 
2.12.3