pagevec.c

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#include <linux/ceph/ceph_debug.h>

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/writeback.h>

#include <linux/ceph/libceph.h>

/*
 * build a vector of user pages
 */
struct page **ceph_get_direct_page_vector(const char __user *data,
                      int num_pages, bool write_page)
{
    struct page **pages;
    int got = 0;
    int rc = 0;

    pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS);
    if (!pages)
        return ERR_PTR(-ENOMEM);

    down_read(&current->mm->mmap_sem);
    while (got < num_pages) {
        rc = get_user_pages(current, current->mm,
            (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
            num_pages - got, write_page, 0, pages + got, NULL);
        if (rc < 0)
            break;
        BUG_ON(rc == 0);
        got += rc;
    }
    up_read(&current->mm->mmap_sem);
    if (rc < 0)
        goto fail;
    return pages;

fail:
    ceph_put_page_vector(pages, got, false);
    return ERR_PTR(rc);
}
EXPORT_SYMBOL(ceph_get_direct_page_vector);

void ceph_put_page_vector(struct page **pages, int num_pages, bool dirty)
{
    int i;

    for (i = 0; i < num_pages; i++) {
        if (dirty)
            set_page_dirty_lock(pages[i]);
        put_page(pages[i]);
    }
    kfree(pages);
}
EXPORT_SYMBOL(ceph_put_page_vector);

void ceph_release_page_vector(struct page **pages, int num_pages)
{
    int i;

    for (i = 0; i < num_pages; i++)
        __free_pages(pages[i], 0);
    kfree(pages);
}
EXPORT_SYMBOL(ceph_release_page_vector);

/*
 * allocate a vector new pages
 */
struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags)
{
    struct page **pages;
    int i;

    pages = kmalloc(sizeof(*pages) * num_pages, flags);
    if (!pages)
        return ERR_PTR(-ENOMEM);
    for (i = 0; i < num_pages; i++) {
        pages[i] = __page_cache_alloc(flags);
        if (pages[i] == NULL) {
            ceph_release_page_vector(pages, i);
            return ERR_PTR(-ENOMEM);
        }
    }
    return pages;
}
EXPORT_SYMBOL(ceph_alloc_page_vector);

/*
 * copy user data into a page vector
 */
int ceph_copy_user_to_page_vector(struct page **pages,
                     const char __user *data,
                     loff_t off, size_t len)
{
    int i = 0;
    int po = off & ~PAGE_CACHE_MASK;
    int left = len;
    int l, bad;

    while (left > 0) {
        l = min_t(int, PAGE_CACHE_SIZE-po, left);
        bad = copy_from_user(page_address(pages[i]) + po, data, l);
        if (bad == l)
            return -EFAULT;
        data += l - bad;
        left -= l - bad;
        po += l - bad;
        if (po == PAGE_CACHE_SIZE) {
            po = 0;
            i++;
        }
    }
    return len;
}
EXPORT_SYMBOL(ceph_copy_user_to_page_vector);

int ceph_copy_to_page_vector(struct page **pages,
                    const char *data,
                    loff_t off, size_t len)
{
    int i = 0;
    size_t po = off & ~PAGE_CACHE_MASK;
    size_t left = len;
    size_t l;

    while (left > 0) {
        l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
        memcpy(page_address(pages[i]) + po, data, l);
        data += l;
        left -= l;
        po += l;
        if (po == PAGE_CACHE_SIZE) {
            po = 0;
            i++;
        }
    }
    return len;
}
EXPORT_SYMBOL(ceph_copy_to_page_vector);

int ceph_copy_from_page_vector(struct page **pages,
                    char *data,
                    loff_t off, size_t len)
{
    int i = 0;
    size_t po = off & ~PAGE_CACHE_MASK;
    size_t left = len;
    size_t l;

    while (left > 0) {
        l = min_t(size_t, PAGE_CACHE_SIZE-po, left);
        memcpy(data, page_address(pages[i]) + po, l);
        data += l;
        left -= l;
        po += l;
        if (po == PAGE_CACHE_SIZE) {
            po = 0;
            i++;
        }
    }
    return len;
}
EXPORT_SYMBOL(ceph_copy_from_page_vector);

/*
 * copy user data from a page vector into a user pointer
 */
int ceph_copy_page_vector_to_user(struct page **pages,
                     char __user *data,
                     loff_t off, size_t len)
{
    int i = 0;
    int po = off & ~PAGE_CACHE_MASK;
    int left = len;
    int l, bad;

    while (left > 0) {
        l = min_t(int, left, PAGE_CACHE_SIZE-po);
        bad = copy_to_user(data, page_address(pages[i]) + po, l);
        if (bad == l)
            return -EFAULT;
        data += l - bad;
        left -= l - bad;
        if (po) {
            po += l - bad;
            if (po == PAGE_CACHE_SIZE)
                po = 0;
        }
        i++;
    }
    return len;
}
EXPORT_SYMBOL(ceph_copy_page_vector_to_user);

/*
 * Zero an extent within a page vector.  Offset is relative to the
 * start of the first page.
 */
void ceph_zero_page_vector_range(int off, int len, struct page **pages)
{
    int i = off >> PAGE_CACHE_SHIFT;

    off &= ~PAGE_CACHE_MASK;

    dout("zero_page_vector_page %u~%u\n", off, len);

    /* leading partial page? */
    if (off) {
        int end = min((int)PAGE_CACHE_SIZE, off + len);
        dout("zeroing %d %p head from %d\n", i, pages[i],
             (int)off);
        zero_user_segment(pages[i], off, end);
        len -= (end - off);
        i++;
    }
    while (len >= PAGE_CACHE_SIZE) {
        dout("zeroing %d %p len=%d\n", i, pages[i], len);
        zero_user_segment(pages[i], 0, PAGE_CACHE_SIZE);
        len -= PAGE_CACHE_SIZE;
        i++;
    }
    /* trailing partial page? */
    if (len) {
        dout("zeroing %d %p tail to %d\n", i, pages[i], (int)len);
        zero_user_segment(pages[i], 0, len);
    }
}
EXPORT_SYMBOL(ceph_zero_page_vector_range);