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Date: Sun, 22 Dec 2013 16:49:48 -0500
From: Matthew Wilcox <matthew.r.wilcox@...el.com>
To: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Cc: Matthew Wilcox <matthew.r.wilcox@...el.com>
Subject: [PATCH v4 21/22] Add support for pmd_faults
Introduce the vm_ops ->pmd_fault handler, add a vm_insert_pfn_pmd function
and create an xip_pmd_fault handler.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
---
fs/ext2/file.c | 9 ++++-
fs/ext4/file.c | 9 ++++-
fs/xip.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/fs.h | 8 ++---
include/linux/mm.h | 4 +++
mm/memory.c | 50 +++++++++++++++++++++++---
6 files changed, 169 insertions(+), 12 deletions(-)
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index 6e6e803..7d6e492 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -31,8 +31,15 @@ static int ext2_xip_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
return xip_fault(vma, vmf, ext2_get_block);
}
+static int ext2_xip_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned int flags)
+{
+ return xip_pmd_fault(vma, addr, pmd, flags, ext2_get_block);
+}
+
static const struct vm_operations_struct ext2_xip_vm_ops = {
.fault = ext2_xip_fault,
+ .pmd_fault = ext2_xip_pmd_fault,
.remap_pages = generic_file_remap_pages,
};
@@ -43,7 +50,7 @@ static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
file_accessed(file);
vma->vm_ops = &ext2_xip_vm_ops;
- vma->vm_flags |= VM_MIXEDMAP;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
return 0;
}
#else
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index d6ae6be..6211f56 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -205,8 +205,15 @@ static int ext4_xip_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
/* Is this the right get_block? */
}
+static int ext4_xip_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned int flags)
+{
+ return xip_pmd_fault(vma, addr, pmd, flags, ext4_get_block);
+}
+
static const struct vm_operations_struct ext4_xip_vm_ops = {
.fault = ext4_xip_fault,
+ .pmd_fault = ext4_xip_pmd_fault,
.remap_pages = generic_file_remap_pages,
};
#else
@@ -224,7 +231,7 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
file_accessed(file);
if (IS_XIP(file_inode(file))) {
vma->vm_ops = &ext4_xip_vm_ops;
- vma->vm_flags |= VM_MIXEDMAP;
+ vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
} else {
vma->vm_ops = &ext4_file_vm_ops;
}
diff --git a/fs/xip.c b/fs/xip.c
index e6e52ee..d032838 100644
--- a/fs/xip.c
+++ b/fs/xip.c
@@ -273,6 +273,107 @@ int xip_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}
EXPORT_SYMBOL_GPL(xip_fault);
+/*
+ * The 'colour' (ie low bits) within a PMD of a page offset. This comes up
+ * more often than one might expect in the below function.
+ */
+#define PG_PMD_COLOUR ((PMD_SIZE >> PAGE_SHIFT) - 1)
+
+/*
+ * We are willing to use a PMD mapping to cover the end of a file if it
+ * could be mapped by a complete PMD's worth of PTEs. That is, the last
+ * part of the file might be slightly smaller than PMD_SIZE, but as long
+ * as it's at least (PMD_SIZE - PAGE_SIZE + 1) bytes long, we allow the
+ * PMD mapping.
+ */
+static int do_xip_pmd_fault(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmd, unsigned int flags, get_block_t get_block)
+{
+ struct file *file = vma->vm_file;
+ struct inode *inode = file_inode(file);
+ struct address_space *mapping = file->f_mapping;
+ struct buffer_head bh;
+ long length;
+ pgoff_t size, pgoff;
+ sector_t block;
+ unsigned long pfn;
+
+ /* Fall back to PTEs if we're going to COW */
+ if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED))
+ return VM_FAULT_FALLBACK;
+
+ pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (pgoff >= size)
+ return VM_FAULT_SIGBUS;
+ if ((pgoff | PG_PMD_COLOUR) >= size)
+ return VM_FAULT_FALLBACK;
+
+ memset(&bh, 0, sizeof(bh));
+ block = ((sector_t)pgoff & ~PG_PMD_COLOUR) <<
+ (PAGE_SHIFT - inode->i_blkbits);
+
+ /* Start by seeing if we already have an allocated block */
+ bh.b_size = PMD_SIZE;
+ length = get_block(inode, block, &bh, 0);
+ if (length)
+ return VM_FAULT_SIGBUS;
+ if (buffer_mapped(&bh) && bh.b_size == PMD_SIZE)
+ goto insert;
+
+ /* Next, try to allocate the whole thing */
+ bh.b_size = PMD_SIZE;
+ length = get_block(inode, block, &bh, 1);
+ if (length)
+ return VM_FAULT_SIGBUS;
+ if (bh.b_size == PMD_SIZE)
+ goto insert;
+
+ return VM_FAULT_FALLBACK;
+
+ insert:
+ length = xip_get_pfn(inode, &bh, &pfn);
+ if (length < 0)
+ return VM_FAULT_SIGBUS;
+ if (length < PMD_SIZE)
+ return VM_FAULT_FALLBACK;
+ if (pfn & PG_PMD_COLOUR)
+ return VM_FAULT_FALLBACK; /* not aligned */
+
+ /* We must recheck i_size under i_mmap_mutex */
+ mutex_lock(&mapping->i_mmap_mutex);
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if ((pgoff | PG_PMD_COLOUR) < size)
+ length = vm_insert_pfn_pmd(vma, address, pmd, pfn);
+ mutex_unlock(&mapping->i_mmap_mutex);
+
+ if (pgoff >= size)
+ return VM_FAULT_SIGBUS;
+ if ((pgoff | PG_PMD_COLOUR) >= size)
+ return VM_FAULT_FALLBACK;
+ if (length == -ENOMEM)
+ return VM_FAULT_OOM;
+ /* -EBUSY is fine, somebody else faulted on the same PMD */
+ if (length != -EBUSY)
+ BUG_ON(length);
+ return VM_FAULT_NOPAGE;
+}
+
+int xip_pmd_fault(struct vm_area_struct *vma, unsigned long address,
+ pmd_t *pmd, unsigned int flags, get_block_t get_block)
+{
+ int result;
+ struct super_block *sb = file_inode(vma->vm_file)->i_sb;
+
+ sb_start_pagefault(sb);
+ file_update_time(vma->vm_file);
+ result = do_xip_pmd_fault(vma, address, pmd, flags, get_block);
+ sb_end_pagefault(sb);
+
+ return result;
+}
+EXPORT_SYMBOL_GPL(xip_pmd_fault);
+
/**
* xip_zero_page_range - zero a range within a page of an XIP file
* @inode: The file being truncated
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3a4a217..e789218 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2513,6 +2513,8 @@ int xip_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
ssize_t xip_do_io(int rw, struct kiocb *, struct inode *, const struct iovec *,
loff_t, unsigned segs, get_block_t, dio_iodone_t, int flags);
int xip_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);
+int xip_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *,
+ unsigned int flags, get_block_t);
#else
static inline int xip_clear_blocks(struct inode *i, sector_t blk, long sz)
{
@@ -2531,12 +2533,6 @@ static inline ssize_t xip_do_io(int rw, struct kiocb *iocb, struct inode *inode,
{
return -ENOTTY;
}
-
-static inline int xip_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
- get_block_t gb)
-{
- return 0;
-}
#endif
/* PAGE_CACHE_ALIGN is defined in pagemap.h */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e07c57c..d48913d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -212,6 +212,8 @@ struct vm_operations_struct {
void (*open)(struct vm_area_struct * area);
void (*close)(struct vm_area_struct * area);
int (*fault)(struct vm_area_struct *vma, struct vm_fault *vmf);
+ int (*pmd_fault)(struct vm_area_struct *, unsigned long address,
+ pmd_t *, unsigned int flags);
/* notification that a previously read-only page is about to become
* writable, if an error is returned it will cause a SIGBUS */
@@ -1857,6 +1859,8 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn);
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn);
+int vm_insert_pfn_pmd(struct vm_area_struct *, unsigned long addr, pmd_t *,
+ unsigned long pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/mm/memory.c b/mm/memory.c
index ecd63fe..0d332cf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2249,6 +2249,41 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
}
EXPORT_SYMBOL(vm_insert_mixed);
+static int insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned long pfn, pgprot_t prot)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ int retval;
+ pmd_t entry;
+ spinlock_t *ptl;
+
+ ptl = pmd_lock(mm, pmd);
+ retval = -EBUSY;
+ if (!pmd_none(*pmd))
+ goto out_unlock;
+
+ /* Ok, finally just insert the thing.. */
+ entry = pfn_pmd(pfn, prot); /* XXX: pmd_mkspecial? */
+ set_pmd_at(mm, addr, pmd, entry);
+ update_mmu_cache_pmd(vma, addr, pmd);
+
+ retval = 0;
+ out_unlock:
+ spin_unlock(ptl);
+ return retval;
+}
+
+int vm_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
+ pmd_t *pmd, unsigned long pfn)
+{
+ BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
+
+ if (addr < vma->vm_start || addr >= vma->vm_end)
+ return -EFAULT;
+ return insert_pfn_pmd(vma, addr, pmd, pfn, vma->vm_page_prot);
+}
+EXPORT_SYMBOL(vm_insert_pfn_pmd);
+
/*
* maps a range of physical memory into the requested pages. the old
* mappings are removed. any references to nonexistent pages results
@@ -3630,6 +3665,16 @@ out:
return 0;
}
+static int create_huge_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmd, unsigned int flags)
+{
+ if (!vma->vm_ops)
+ return do_huge_pmd_anonymous_page(mm, vma, address, pmd, flags);
+ if (vma->vm_ops->pmd_fault)
+ return vma->vm_ops->pmd_fault(vma, address, pmd, flags);
+ return VM_FAULT_FALLBACK;
+}
+
/*
* These routines also need to handle stuff like marking pages dirty
* and/or accessed for architectures that don't do it in hardware (most
@@ -3722,10 +3767,7 @@ retry:
if (!pmd)
return VM_FAULT_OOM;
if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
- int ret = VM_FAULT_FALLBACK;
- if (!vma->vm_ops)
- ret = do_huge_pmd_anonymous_page(mm, vma, address,
- pmd, flags);
+ int ret = create_huge_pmd(mm, vma, address, pmd, flags);
if (!(ret & VM_FAULT_FALLBACK))
return ret;
} else {
--
1.8.4.rc3
--
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