diff options
| -rw-r--r-- | fs/open.c | 4 | ||||
| -rw-r--r-- | include/linux/fs.h | 18 | ||||
| -rw-r--r-- | include/linux/rmap.h | 6 | ||||
| -rw-r--r-- | mm/Makefile | 1 | ||||
| -rw-r--r-- | mm/filemap.c | 74 | ||||
| -rw-r--r-- | mm/filemap.h | 94 | ||||
| -rw-r--r-- | mm/filemap_xip.c | 581 | ||||
| -rw-r--r-- | mm/rmap.c | 4 |
8 files changed, 707 insertions, 75 deletions
@@ -808,7 +808,9 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags) /* NB: we're sure to have correct a_ops only after f_op->open */ if (f->f_flags & O_DIRECT) { - if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO) { + if (!f->f_mapping->a_ops || + ((!f->f_mapping->a_ops->direct_IO) && + (!f->f_mapping->a_ops->get_xip_page))) { fput(f); f = ERR_PTR(-EINVAL); } diff --git a/include/linux/fs.h b/include/linux/fs.h index 929bf8d..79c0faf 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -330,6 +330,8 @@ struct address_space_operations { int (*releasepage) (struct page *, int); ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, loff_t offset, unsigned long nr_segs); + struct page* (*get_xip_page)(struct address_space *, sector_t, + int); }; struct backing_dev_info; @@ -1497,6 +1499,22 @@ extern loff_t remote_llseek(struct file *file, loff_t offset, int origin); extern int generic_file_open(struct inode * inode, struct file * filp); extern int nonseekable_open(struct inode * inode, struct file * filp); +#ifdef CONFIG_FS_XIP +extern ssize_t xip_file_aio_read(struct kiocb *iocb, char __user *buf, + size_t count, loff_t pos); +extern ssize_t xip_file_readv(struct file *filp, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos); +extern ssize_t xip_file_sendfile(struct file *in_file, loff_t *ppos, + size_t count, read_actor_t actor, + void *target); +extern int xip_file_mmap(struct file * file, struct vm_area_struct * vma); +extern ssize_t xip_file_aio_write(struct kiocb *iocb, const char __user *buf, + size_t count, loff_t pos); +extern ssize_t xip_file_writev(struct file *file, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos); +extern int xip_truncate_page(struct address_space *mapping, loff_t from); +#endif + static inline void do_generic_file_read(struct file * filp, loff_t *ppos, read_descriptor_t * desc, read_actor_t actor) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 11b484e..e80fb7ee 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -93,6 +93,12 @@ int page_referenced(struct page *, int is_locked, int ignore_token); int try_to_unmap(struct page *); /* + * Called from mm/filemap_xip.c to unmap empty zero page + */ +pte_t *page_check_address(struct page *, struct mm_struct *, unsigned long); + + +/* * Used by swapoff to help locate where page is expected in vma. */ unsigned long page_address_in_vma(struct page *, struct vm_area_struct *); diff --git a/mm/Makefile b/mm/Makefile index 8f70ffd..4cd69e3 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -19,3 +19,4 @@ obj-$(CONFIG_SPARSEMEM) += sparse.o obj-$(CONFIG_SHMEM) += shmem.o obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o +obj-$(CONFIG_FS_XIP) += filemap_xip.o diff --git a/mm/filemap.c b/mm/filemap.c index a3598b5..7332194 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -28,6 +28,7 @@ #include <linux/blkdev.h> #include <linux/security.h> #include <linux/syscalls.h> +#include "filemap.h" /* * FIXME: remove all knowledge of the buffer layer from the core VM */ @@ -1714,32 +1715,7 @@ int remove_suid(struct dentry *dentry) } EXPORT_SYMBOL(remove_suid); -/* - * Copy as much as we can into the page and return the number of bytes which - * were sucessfully copied. If a fault is encountered then clear the page - * out to (offset+bytes) and return the number of bytes which were copied. - */ -static inline size_t -filemap_copy_from_user(struct page *page, unsigned long offset, - const char __user *buf, unsigned bytes) -{ - char *kaddr; - int left; - - kaddr = kmap_atomic(page, KM_USER0); - left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); - kunmap_atomic(kaddr, KM_USER0); - - if (left != 0) { - /* Do it the slow way */ - kaddr = kmap(page); - left = __copy_from_user(kaddr + offset, buf, bytes); - kunmap(page); - } - return bytes - left; -} - -static size_t +size_t __filemap_copy_from_user_iovec(char *vaddr, const struct iovec *iov, size_t base, size_t bytes) { @@ -1767,52 +1743,6 @@ __filemap_copy_from_user_iovec(char *vaddr, } /* - * This has the same sideeffects and return value as filemap_copy_from_user(). - * The difference is that on a fault we need to memset the remainder of the - * page (out to offset+bytes), to emulate filemap_copy_from_user()'s - * single-segment behaviour. - */ -static inline size_t -filemap_copy_from_user_iovec(struct page *page, unsigned long offset, - const struct iovec *iov, size_t base, size_t bytes) -{ - char *kaddr; - size_t copied; - - kaddr = kmap_atomic(page, KM_USER0); - copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, - base, bytes); - kunmap_atomic(kaddr, KM_USER0); - if (copied != bytes) { - kaddr = kmap(page); - copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, - base, bytes); - kunmap(page); - } - return copied; -} - -static inline void -filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) -{ - const struct iovec *iov = *iovp; - size_t base = *basep; - - while (bytes) { - int copy = min(bytes, iov->iov_len - base); - - bytes -= copy; - base += copy; - if (iov->iov_len == base) { - iov++; - base = 0; - } - } - *iovp = iov; - *basep = base; -} - -/* * Performs necessary checks before doing a write * * Can adjust writing position aor amount of bytes to write. diff --git a/mm/filemap.h b/mm/filemap.h new file mode 100644 index 0000000..c2d0546 --- /dev/null +++ b/mm/filemap.h @@ -0,0 +1,94 @@ +/* + * linux/mm/filemap.h + * + * Copyright (C) 1994-1999 Linus Torvalds + */ + +#ifndef __FILEMAP_H +#define __FILEMAP_H + +#include <linux/types.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/uio.h> +#include <linux/config.h> +#include <asm/uaccess.h> + +extern size_t +__filemap_copy_from_user_iovec(char *vaddr, + const struct iovec *iov, + size_t base, + size_t bytes); + +/* + * Copy as much as we can into the page and return the number of bytes which + * were sucessfully copied. If a fault is encountered then clear the page + * out to (offset+bytes) and return the number of bytes which were copied. + */ +static inline size_t +filemap_copy_from_user(struct page *page, unsigned long offset, + const char __user *buf, unsigned bytes) +{ + char *kaddr; + int left; + + kaddr = kmap_atomic(page, KM_USER0); + left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); + kunmap_atomic(kaddr, KM_USER0); + + if (left != 0) { + /* Do it the slow way */ + kaddr = kmap(page); + left = __copy_from_user(kaddr + offset, buf, bytes); + kunmap(page); + } + return bytes - left; +} + +/* + * This has the same sideeffects and return value as filemap_copy_from_user(). + * The difference is that on a fault we need to memset the remainder of the + * page (out to offset+bytes), to emulate filemap_copy_from_user()'s + * single-segment behaviour. + */ +static inline size_t +filemap_copy_from_user_iovec(struct page *page, unsigned long offset, + const struct iovec *iov, size_t base, size_t bytes) +{ + char *kaddr; + size_t copied; + + kaddr = kmap_atomic(page, KM_USER0); + copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, + base, bytes); + kunmap_atomic(kaddr, KM_USER0); + if (copied != bytes) { + kaddr = kmap(page); + copied = __filemap_copy_from_user_iovec(kaddr + offset, iov, + base, bytes); + kunmap(page); + } + return copied; +} + +static inline void +filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes) +{ + const struct iovec *iov = *iovp; + size_t base = *basep; + + while (bytes) { + int copy = min(bytes, iov->iov_len - base); + + bytes -= copy; + base += copy; + if (iov->iov_len == base) { + iov++; + base = 0; + } + } + *iovp = iov; + *basep = base; +} +#endif diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c new file mode 100644 index 0000000..7d63acd --- /dev/null +++ b/mm/filemap_xip.c @@ -0,0 +1,581 @@ +/* + * linux/mm/filemap_xip.c + * + * Copyright (C) 2005 IBM Corporation + * Author: Carsten Otte <cotte@de.ibm.com> + * + * derived from linux/mm/filemap.c - Copyright (C) Linus Torvalds + * + */ + +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/module.h> +#include <linux/uio.h> +#include <linux/rmap.h> +#include <asm/tlbflush.h> +#include "filemap.h" + +/* + * This is a file read routine for execute in place files, and uses + * the mapping->a_ops->get_xip_page() function for the actual low-level + * stuff. + * + * Note the struct file* is not used at all. It may be NULL. + */ +static void +do_xip_mapping_read(struct address_space *mapping, + struct file_ra_state *_ra, + struct file *filp, + loff_t *ppos, + read_descriptor_t *desc, + read_actor_t actor) +{ + struct inode *inode = mapping->host; + unsigned long index, end_index, offset; + loff_t isize; + + BUG_ON(!mapping->a_ops->get_xip_page); + + index = *ppos >> PAGE_CACHE_SHIFT; + offset = *ppos & ~PAGE_CACHE_MASK; + + isize = i_size_read(inode); + if (!isize) + goto out; + + end_index = (isize - 1) >> PAGE_CACHE_SHIFT; + for (;;) { + struct page *page; + unsigned long nr, ret; + + /* nr is the maximum number of bytes to copy from this page */ + nr = PAGE_CACHE_SIZE; + if (index >= end_index) { + if (index > end_index) + goto out; + nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; + if (nr <= offset) { + goto out; + } + } + nr = nr - offset; + + page = mapping->a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + if (!page) + goto no_xip_page; + if (unlikely(IS_ERR(page))) { + if (PTR_ERR(page) == -ENODATA) { + /* sparse */ + page = virt_to_page(empty_zero_page); + } else { + desc->error = PTR_ERR(page); + goto out; + } + } else + BUG_ON(!PageUptodate(page)); + + /* If users can be writing to this page using arbitrary + * virtual addresses, take care about potential aliasing + * before reading the page on the kernel side. + */ + if (mapping_writably_mapped(mapping)) + flush_dcache_page(page); + + /* + * Ok, we have the page, and it's up-to-date, so + * now we can copy it to user space... + * + * The actor routine returns how many bytes were actually used.. + * NOTE! This may not be the same as how much of a user buffer + * we filled up (we may be padding etc), so we can only update + * "pos" here (the actor routine has to update the user buffer + * pointers and the remaining count). + */ + ret = actor(desc, page, offset, nr); + offset += ret; + index += offset >> PAGE_CACHE_SHIFT; + offset &= ~PAGE_CACHE_MASK; + + if (ret == nr && desc->count) + continue; + goto out; + +no_xip_page: + /* Did not get the page. Report it */ + desc->error = -EIO; + goto out; + } + +out: + *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; + if (filp) + file_accessed(filp); +} + +/* + * This is the "read()" routine for all filesystems + * that uses the get_xip_page address space operation. + */ +static ssize_t +__xip_file_aio_read(struct kiocb *iocb, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos) +{ + struct file *filp = iocb->ki_filp; + ssize_t retval; + unsigned long seg; + size_t count; + + count = 0; + for (seg = 0; seg < nr_segs; seg++) { + const struct iovec *iv = &iov[seg]; + + /* + * If any segment has a negative length, or the cumulative + * length ever wraps negative then return -EINVAL. + */ + count += iv->iov_len; + if (unlikely((ssize_t)(count|iv->iov_len) < 0)) + return -EINVAL; + if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len)) + continue; + if (seg == 0) + return -EFAULT; + nr_segs = seg; + count -= iv->iov_len; /* This segment is no good */ + break; + } + + retval = 0; + if (count) { + for (seg = 0; seg < nr_segs; seg++) { + read_descriptor_t desc; + + desc.written = 0; + desc.arg.buf = iov[seg].iov_base; + desc.count = iov[seg].iov_len; + if (desc.count == 0) + continue; + desc.error = 0; + do_xip_mapping_read(filp->f_mapping, &filp->f_ra, filp, + ppos, &desc, file_read_actor); + retval += desc.written; + if (!retval) { + retval = desc.error; + break; + } + } + } + return retval; +} + +ssize_t +xip_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, + loff_t pos) +{ + struct iovec local_iov = { .iov_base = buf, .iov_len = count }; + + BUG_ON(iocb->ki_pos != pos); + return __xip_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos); +} +EXPORT_SYMBOL_GPL(xip_file_aio_read); + +ssize_t +xip_file_readv(struct file *filp, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos) +{ + struct kiocb kiocb; + + init_sync_kiocb(&kiocb, filp); + return __xip_file_aio_read(&kiocb, iov, nr_segs, ppos); +} +EXPORT_SYMBOL_GPL(xip_file_readv); + +ssize_t +xip_file_sendfile(struct file *in_file, loff_t *ppos, + size_t count, read_actor_t actor, void *target) +{ + read_descriptor_t desc; + + if (!count) + return 0; + + desc.written = 0; + desc.count = count; + desc.arg.data = target; + desc.error = 0; + + do_xip_mapping_read(in_file->f_mapping, &in_file->f_ra, in_file, + ppos, &desc, actor); + if (desc.written) + return desc.written; + return desc.error; +} +EXPORT_SYMBOL_GPL(xip_file_sendfile); + +/* + * __xip_unmap is invoked from xip_unmap and + * xip_write + * + * This function walks all vmas of the address_space and unmaps the + * empty_zero_page when found at pgoff. Should it go in rmap.c? + */ +static void +__xip_unmap (struct address_space * mapping, + unsigned long pgoff) +{ + struct vm_area_struct *vma; + struct mm_struct *mm; + struct prio_tree_iter iter; + unsigned long address; + pte_t *pte; + pte_t pteval; + + spin_lock(&mapping->i_mmap_lock); + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + mm = vma->vm_mm; + address = vma->vm_start + + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); + BUG_ON(address < vma->vm_start || address >= vma->vm_end); + /* + * We need the page_table_lock to protect us from page faults, + * munmap, fork, etc... + */ + pte = page_check_address(virt_to_page(empty_zero_page), mm, + address); + if (!IS_ERR(pte)) { + /* Nuke the page table entry. */ + flush_cache_page(vma, address, pte_pfn(pte)); + pteval = ptep_clear_flush(vma, address, pte); + BUG_ON(pte_dirty(pteval)); + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + } + } + spin_unlock(&mapping->i_mmap_lock); +} + +/* + * xip_nopage() is invoked via the vma operations vector for a + * mapped memory region to read in file data during a page fault. + * + * This function is derived from filemap_nopage, but used for execute in place + */ +static struct page * +xip_file_nopage(struct vm_area_struct * area, + unsigned long address, + int *type) +{ + struct file *file = area->vm_file; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + struct page *page; + unsigned long size, pgoff, endoff; + + pgoff = ((address - area->vm_start) >> PAGE_CACHE_SHIFT) + + area->vm_pgoff; + endoff = ((area->vm_end - area->vm_start) >> PAGE_CACHE_SHIFT) + + area->vm_pgoff; + + size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + if (pgoff >= size) { + return NULL; + } + + page = mapping->a_ops->get_xip_page(mapping, pgoff*(PAGE_SIZE/512), 0); + if (!IS_ERR(page)) { + BUG_ON(!PageUptodate(page)); + return page; + } + if (PTR_ERR(page) != -ENODATA) + return NULL; + + /* sparse block */ + if ((area->vm_flags & (VM_WRITE | VM_MAYWRITE)) && + (area->vm_flags & (VM_SHARED| VM_MAYSHARE)) && + (!(mapping->host->i_sb->s_flags & MS_RDONLY))) { + /* maybe shared writable, allocate new block */ + page = mapping->a_ops->get_xip_page (mapping, + pgoff*(PAGE_SIZE/512), 1); + if (IS_ERR(page)) + return NULL; + BUG_ON(!PageUptodate(page)); + /* unmap page at pgoff from all other vmas */ + __xip_unmap(mapping, pgoff); + } else { + /* not shared and writable, use empty_zero_page */ + page = virt_to_page(empty_zero_page); + } + + return page; +} + +static struct vm_operations_struct xip_file_vm_ops = { + .nopage = xip_file_nopage, +}; + +int xip_file_mmap(struct file * file, struct vm_area_struct * vma) +{ + BUG_ON(!file->f_mapping->a_ops->get_xip_page); + + file_accessed(file); + vma->vm_ops = &xip_file_vm_ops; + return 0; +} +EXPORT_SYMBOL_GPL(xip_file_mmap); + +static ssize_t +do_xip_file_write(struct kiocb *iocb, const struct iovec *iov, + unsigned long nr_segs, loff_t pos, loff_t *ppos, + size_t count) +{ + struct file *file = iocb->ki_filp; + struct address_space * mapping = file->f_mapping; + struct address_space_operations *a_ops = mapping->a_ops; + struct inode *inode = mapping->host; + long status = 0; + struct page *page; + size_t bytes; + const struct iovec *cur_iov = iov; /* current iovec */ + size_t iov_base = 0; /* offset in the current iovec */ + char __user *buf; + ssize_t written = 0; + + BUG_ON(!mapping->a_ops->get_xip_page); + + buf = iov->iov_base; + do { + unsigned long index; + unsigned long offset; + size_t copied; + + offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ + index = pos >> PAGE_CACHE_SHIFT; + bytes = PAGE_CACHE_SIZE - offset; + if (bytes > count) + bytes = count; + + /* + * Bring in the user page that we will copy from _first_. + * Otherwise there's a nasty deadlock on copying from the + * same page as we're writing to, without it being marked + * up-to-date. + */ + fault_in_pages_readable(buf, bytes); + + page = a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + if (IS_ERR(page) && (PTR_ERR(page) == -ENODATA)) { + /* we allocate a new page unmap it */ + page = a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 1); + if (!IS_ERR(page)) + /* unmap page at pgoff from all other vmas */ + __xip_unmap(mapping, index); + + } + + if (IS_ERR(page)) { + status = PTR_ERR(page); + break; + } + + BUG_ON(!PageUptodate(page)); + + if (likely(nr_segs == 1)) + copied = filemap_copy_from_user(page, offset, + buf, bytes); + else + copied = filemap_copy_from_user_iovec(page, offset, + cur_iov, iov_base, bytes); + flush_dcache_page(page); + if (likely(copied > 0)) { + status = copied; + + if (status >= 0) { + written += status; + count -= status; + pos += status; + buf += status; + if (unlikely(nr_segs > 1)) + filemap_set_next_iovec(&cur_iov, + &iov_base, status); + } + } + if (unlikely(copied != bytes)) + if (status >= 0) + status = -EFAULT; + if (status < 0) + break; + } while (count); + *ppos = pos; + /* + * No need to use i_size_read() here, the i_size + * cannot change under us because we hold i_sem. + */ + if (pos > inode->i_size) { + i_size_write(inode, pos); + mark_inode_dirty(inode); + } + + return written ? written : status; +} + +static ssize_t +xip_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos) +{ + struct file *file = iocb->ki_filp; + struct address_space * mapping = file->f_mapping; + size_t ocount; /* original count */ + size_t count; /* after file limit checks */ + struct inode *inode = mapping->host; + unsigned long seg; + loff_t pos; + ssize_t written; + ssize_t err; + + ocount = 0; + for (seg = 0; seg < nr_segs; seg++) { + const struct iovec *iv = &iov[seg]; + + /* + * If any segment has a negative length, or the cumulative + * length ever wraps negative then return -EINVAL. + */ + ocount += iv->iov_len; + if (unlikely((ssize_t)(ocount|iv->iov_len) < 0)) + return -EINVAL; + if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len)) + continue; + if (seg == 0) + return -EFAULT; + nr_segs = seg; + ocount -= iv->iov_len; /* This segment is no good */ + break; + } + + count = ocount; + pos = *ppos; + + vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); + + written = 0; + + err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); + if (err) + goto out; + + if (count == 0) + goto out; + + err = remove_suid(file->f_dentry); + if (err) + goto out; + + inode_update_time(inode, 1); + + /* use execute in place to copy directly to disk */ + written = do_xip_file_write (iocb, iov, + nr_segs, pos, ppos, count); + out: + return written ? written : err; +} + +static ssize_t +__xip_file_write_nolock(struct file *file, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos) +{ + struct kiocb kiocb; + + init_sync_kiocb(&kiocb, file); + return xip_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos); +} + +ssize_t +xip_file_aio_write(struct kiocb *iocb, const char __user *buf, + size_t count, loff_t pos) +{ + struct file *file = iocb->ki_filp; + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + ssize_t ret; + struct iovec local_iov = { .iov_base = (void __user *)buf, + .iov_len = count }; + + BUG_ON(iocb->ki_pos != pos); + + down(&inode->i_sem); + ret = xip_file_aio_write_nolock(iocb, &local_iov, 1, &iocb->ki_pos); + up(&inode->i_sem); + return ret; +} +EXPORT_SYMBOL_GPL(xip_file_aio_write); + +ssize_t xip_file_writev(struct file *file, const struct iovec *iov, + unsigned long nr_segs, loff_t *ppos) +{ + struct address_space *mapping = file->f_mapping; + struct inode *inode = mapping->host; + ssize_t ret; + + down(&inode->i_sem); + ret = __xip_file_write_nolock(file, iov, nr_segs, ppos); + up(&inode->i_sem); + return ret; +} +EXPORT_SYMBOL_GPL(xip_file_writev); + +/* + * truncate a page used for execute in place + * functionality is analog to block_truncate_page but does use get_xip_page + * to get the page instead of page cache + */ +int +xip_truncate_page(struct address_space *mapping, loff_t from) +{ + pgoff_t index = from >> PAGE_CACHE_SHIFT; + unsigned offset = from & (PAGE_CACHE_SIZE-1); + unsigned blocksize; + unsigned length; + struct page *page; + void *kaddr; + int err; + + BUG_ON(!mapping->a_ops->get_xip_page); + + blocksize = 1 << mapping->host->i_blkbits; + length = offset & (blocksize - 1); + + /* Block boundary? Nothing to do */ + if (!length) + return 0; + + length = blocksize - length; + + page = mapping->a_ops->get_xip_page(mapping, + index*(PAGE_SIZE/512), 0); + err = -ENOMEM; + if (!page) + goto out; + if (unlikely(IS_ERR(page))) { + if (PTR_ERR(page) == -ENODATA) { + /* Hole? No need to truncate */ + return 0; + } else { + err = PTR_ERR(page); + goto out; + } + } else + BUG_ON(!PageUptodate(page)); + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + offset, 0, length); + kunmap_atomic(kaddr, KM_USER0); + + flush_dcache_page(page); + err = 0; +out: + return err; +} +EXPORT_SYMBOL_GPL(xip_truncate_page); @@ -247,8 +247,8 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) * * On success returns with mapped pte and locked mm->page_table_lock. */ -static pte_t *page_check_address(struct page *page, struct mm_struct *mm, - unsigned long address) +pte_t *page_check_address(struct page *page, struct mm_struct *mm, + unsigned long address) { pgd_t *pgd; pud_t *pud; |
