#include <linux/mount.h>
#include <linux/file.h>
+#include <linux/ima.h>
#include "internal.h"
/*
_debug("--- monitor %p %lx ---", page, page->flags);
- if (!PageUptodate(page) && !PageError(page))
- dump_stack();
+ if (!PageUptodate(page) && !PageError(page)) {
+ /* unlocked, not uptodate and not erronous? */
+ _debug("page probably truncated");
+ }
/* remove from the waitqueue */
list_del(&wait->task_list);
}
/*
+ * handle a probably truncated page
+ * - check to see if the page is still relevant and reissue the read if
+ * possible
+ * - return -EIO on error, -ENODATA if the page is gone, -EINPROGRESS if we
+ * must wait again and 0 if successful
+ */
+static int cachefiles_read_reissue(struct cachefiles_object *object,
+ struct cachefiles_one_read *monitor)
+{
+ struct address_space *bmapping = object->backer->d_inode->i_mapping;
+ struct page *backpage = monitor->back_page, *backpage2;
+ int ret;
+
+ kenter("{ino=%lx},{%lx,%lx}",
+ object->backer->d_inode->i_ino,
+ backpage->index, backpage->flags);
+
+ /* skip if the page was truncated away completely */
+ if (backpage->mapping != bmapping) {
+ kleave(" = -ENODATA [mapping]");
+ return -ENODATA;
+ }
+
+ backpage2 = find_get_page(bmapping, backpage->index);
+ if (!backpage2) {
+ kleave(" = -ENODATA [gone]");
+ return -ENODATA;
+ }
+
+ if (backpage != backpage2) {
+ put_page(backpage2);
+ kleave(" = -ENODATA [different]");
+ return -ENODATA;
+ }
+
+ /* the page is still there and we already have a ref on it, so we don't
+ * need a second */
+ put_page(backpage2);
+
+ INIT_LIST_HEAD(&monitor->op_link);
+ add_page_wait_queue(backpage, &monitor->monitor);
+
+ if (trylock_page(backpage)) {
+ ret = -EIO;
+ if (PageError(backpage))
+ goto unlock_discard;
+ ret = 0;
+ if (PageUptodate(backpage))
+ goto unlock_discard;
+
+ kdebug("reissue read");
+ ret = bmapping->a_ops->readpage(NULL, backpage);
+ if (ret < 0)
+ goto unlock_discard;
+ }
+
+ /* but the page may have been read before the monitor was installed, so
+ * the monitor may miss the event - so we have to ensure that we do get
+ * one in such a case */
+ if (trylock_page(backpage)) {
+ _debug("jumpstart %p {%lx}", backpage, backpage->flags);
+ unlock_page(backpage);
+ }
+
+ /* it'll reappear on the todo list */
+ kleave(" = -EINPROGRESS");
+ return -EINPROGRESS;
+
+unlock_discard:
+ unlock_page(backpage);
+ spin_lock_irq(&object->work_lock);
+ list_del(&monitor->op_link);
+ spin_unlock_irq(&object->work_lock);
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/*
* copy data from backing pages to netfs pages to complete a read operation
* - driven by FS-Cache's thread pool
*/
_debug("- copy {%lu}", monitor->back_page->index);
- error = -EIO;
+ recheck:
if (PageUptodate(monitor->back_page)) {
copy_highpage(monitor->netfs_page, monitor->back_page);
pagevec_add(&pagevec, monitor->netfs_page);
fscache_mark_pages_cached(monitor->op, &pagevec);
error = 0;
- }
-
- if (error)
+ } else if (!PageError(monitor->back_page)) {
+ /* the page has probably been truncated */
+ error = cachefiles_read_reissue(object, monitor);
+ if (error == -EINPROGRESS)
+ goto next;
+ goto recheck;
+ } else {
cachefiles_io_error_obj(
object,
"Readpage failed on backing file %lx",
(unsigned long) monitor->back_page->flags);
+ error = -EIO;
+ }
page_cache_release(monitor->back_page);
fscache_put_retrieval(op);
kfree(monitor);
+ next:
/* let the thread pool have some air occasionally */
max--;
if (max < 0 || need_resched()) {
shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;
- op->op.flags = FSCACHE_OP_FAST;
+ op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
+ op->op.flags |= FSCACHE_OP_FAST;
op->op.processor = cachefiles_read_copier;
pagevec_init(&pagevec, 0);
pagevec_init(&pagevec, 0);
- op->op.flags = FSCACHE_OP_FAST;
+ op->op.flags &= FSCACHE_OP_KEEP_FLAGS;
+ op->op.flags |= FSCACHE_OP_FAST;
op->op.processor = cachefiles_read_copier;
INIT_LIST_HEAD(&backpages);
struct cachefiles_cache *cache;
mm_segment_t old_fs;
struct file *file;
- loff_t pos;
+ loff_t pos, eof;
+ size_t len;
void *data;
int ret;
if (IS_ERR(file)) {
ret = PTR_ERR(file);
} else {
+ ima_counts_get(file);
ret = -EIO;
if (file->f_op->write) {
pos = (loff_t) page->index << PAGE_SHIFT;
+
+ /* we mustn't write more data than we have, so we have
+ * to beware of a partial page at EOF */
+ eof = object->fscache.store_limit_l;
+ len = PAGE_SIZE;
+ if (eof & ~PAGE_MASK) {
+ ASSERTCMP(pos, <, eof);
+ if (eof - pos < PAGE_SIZE) {
+ _debug("cut short %llx to %llx",
+ pos, eof);
+ len = eof - pos;
+ ASSERTCMP(pos + len, ==, eof);
+ }
+ }
+
data = kmap(page);
old_fs = get_fs();
set_fs(KERNEL_DS);
ret = file->f_op->write(
- file, (const void __user *) data, PAGE_SIZE,
- &pos);
+ file, (const void __user *) data, len, &pos);
set_fs(old_fs);
kunmap(page);
- if (ret != PAGE_SIZE)
+ if (ret != len)
ret = -EIO;
}
fput(file);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff