3 files changed, 285 insertions, 64 deletions

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 431accd475a7..27089311fbea 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -114,8 +114,9 @@ nomem_lookup_data:
 
 /*
  * attempt to look up the nominated node in this cache
+ * - return -ETIMEDOUT to be scheduled again
  */
-static void cachefiles_lookup_object(struct fscache_object *_object)
+static int cachefiles_lookup_object(struct fscache_object *_object)
 {
         struct cachefiles_lookup_data *lookup_data;
         struct cachefiles_object *parent, *object;
@@ -145,13 +146,15 @@ static void cachefiles_lookup_object(struct fscache_object *_object)
             object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
                 cachefiles_attr_changed(&object->fscache);
 
-        if (ret < 0) {
-                printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n",
-                       ret);
+        if (ret < 0 && ret != -ETIMEDOUT) {
+                if (ret != -ENOBUFS)
+                        printk(KERN_WARNING
+                               "CacheFiles: Lookup failed error %d\n", ret);
                 fscache_object_lookup_error(&object->fscache);
         }
 
         _leave(" [%d]", ret);
+        return ret;
 }
 
 /*
@@ -331,6 +334,7 @@ static void cachefiles_put_object(struct fscache_object *_object)
                 }
 
                 cache = object->fscache.cache;
+                fscache_object_destroy(&object->fscache);
                 kmem_cache_free(cachefiles_object_jar, object);
                 fscache_object_destroyed(cache);
         }
@@ -403,12 +407,26 @@ static int cachefiles_attr_changed(struct fscache_object *_object)
         if (oi_size == ni_size)
                 return 0;
 
-        newattrs.ia_size = ni_size;
-        newattrs.ia_valid = ATTR_SIZE;
-
         cachefiles_begin_secure(cache, &saved_cred);
         mutex_lock(&object->backer->d_inode->i_mutex);
+
+        /* if there's an extension to a partial page at the end of the backing
+         * file, we need to discard the partial page so that we pick up new
+         * data after it */
+        if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
+                _debug("discard tail %llx", oi_size);
+                newattrs.ia_valid = ATTR_SIZE;
+                newattrs.ia_size = oi_size & PAGE_MASK;
+                ret = notify_change(object->backer, &newattrs);
+                if (ret < 0)
+                        goto truncate_failed;
+        }
+
+        newattrs.ia_valid = ATTR_SIZE;
+        newattrs.ia_size = ni_size;
         ret = notify_change(object->backer, &newattrs);
+
+truncate_failed:
         mutex_unlock(&object->backer->d_inode->i_mutex);
         cachefiles_end_secure(cache, saved_cred);
 
diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 4ce818ae39ea..14ac4806e291 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -21,17 +21,81 @@
 #include <linux/security.h>
 #include "internal.h"
 
-static int cachefiles_wait_bit(void *flags)
+#define CACHEFILES_KEYBUF_SIZE 512
+
+/*
+ * dump debugging info about an object
+ */
+static noinline
+void __cachefiles_printk_object(struct cachefiles_object *object,
+                                const char *prefix,
+                                u8 *keybuf)
 {
-        schedule();
-        return 0;
+        struct fscache_cookie *cookie;
+        unsigned keylen, loop;
+
+        printk(KERN_ERR "%sobject: OBJ%x\n",
+               prefix, object->fscache.debug_id);
+        printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
+               prefix, fscache_object_states[object->fscache.state],
+               object->fscache.flags, object->fscache.work.flags,
+               object->fscache.events,
+               object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
+        printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
+               prefix, object->fscache.n_ops, object->fscache.n_in_progress,
+               object->fscache.n_exclusive);
+        printk(KERN_ERR "%sparent=%p\n",
+               prefix, object->fscache.parent);
+
+        spin_lock(&object->fscache.lock);
+        cookie = object->fscache.cookie;
+        if (cookie) {
+                printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
+                       prefix,
+                       object->fscache.cookie,
+                       object->fscache.cookie->parent,
+                       object->fscache.cookie->netfs_data,
+                       object->fscache.cookie->flags);
+                if (keybuf)
+                        keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
+                                                      CACHEFILES_KEYBUF_SIZE);
+                else
+                        keylen = 0;
+        } else {
+                printk(KERN_ERR "%scookie=NULL\n", prefix);
+                keylen = 0;
+        }
+        spin_unlock(&object->fscache.lock);
+
+        if (keylen) {
+                printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
+                for (loop = 0; loop < keylen; loop++)
+                        printk("%02x", keybuf[loop]);
+                printk("'\n");
+        }
+}
+
+/*
+ * dump debugging info about a pair of objects
+ */
+static noinline void cachefiles_printk_object(struct cachefiles_object *object,
+                                              struct cachefiles_object *xobject)
+{
+        u8 *keybuf;
+
+        keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
+        if (object)
+                __cachefiles_printk_object(object, "", keybuf);
+        if (xobject)
+                __cachefiles_printk_object(xobject, "x", keybuf);
+        kfree(keybuf);
 }
 
 /*
  * record the fact that an object is now active
  */
-static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
-                                          struct cachefiles_object *object)
+static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
+                                         struct cachefiles_object *object)
 {
         struct cachefiles_object *xobject;
         struct rb_node **_p, *_parent = NULL;
@@ -42,8 +106,11 @@ static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
 try_again:
         write_lock(&cache->active_lock);
 
-        if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
+        if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
+                printk(KERN_ERR "CacheFiles: Error: Object already active\n");
+                cachefiles_printk_object(object, NULL);
                 BUG();
+        }
 
         dentry = object->dentry;
         _p = &cache->active_nodes.rb_node;
@@ -66,8 +133,8 @@ try_again:
         rb_insert_color(&object->active_node, &cache->active_nodes);
 
         write_unlock(&cache->active_lock);
-        _leave("");
-        return;
+        _leave(" = 0");
+        return 0;
 
         /* an old object from a previous incarnation is hogging the slot - we
          * need to wait for it to be destroyed */
@@ -76,44 +143,70 @@ wait_for_old_object:
                 printk(KERN_ERR "\n");
                 printk(KERN_ERR "CacheFiles: Error:"
                        " Unexpected object collision\n");
-                printk(KERN_ERR "xobject: OBJ%x\n",
-                       xobject->fscache.debug_id);
-                printk(KERN_ERR "xobjstate=%s\n",
-                       fscache_object_states[xobject->fscache.state]);
-                printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);
-                printk(KERN_ERR "xobjevent=%lx [%lx]\n",
-                       xobject->fscache.events, xobject->fscache.event_mask);
-                printk(KERN_ERR "xops=%u inp=%u exc=%u\n",
-                       xobject->fscache.n_ops, xobject->fscache.n_in_progress,
-                       xobject->fscache.n_exclusive);
-                printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",
-                       xobject->fscache.cookie,
-                       xobject->fscache.cookie->parent,
-                       xobject->fscache.cookie->netfs_data,
-                       xobject->fscache.cookie->flags);
-                printk(KERN_ERR "xparent=%p\n",
-                       xobject->fscache.parent);
-                printk(KERN_ERR "object: OBJ%x\n",
-                       object->fscache.debug_id);
-                printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",
-                       object->fscache.cookie,
-                       object->fscache.cookie->parent,
-                       object->fscache.cookie->netfs_data,
-                       object->fscache.cookie->flags);
-                printk(KERN_ERR "parent=%p\n",
-                       object->fscache.parent);
+                cachefiles_printk_object(object, xobject);
                 BUG();
         }
         atomic_inc(&xobject->usage);
         write_unlock(&cache->active_lock);
 
-        _debug(">>> wait");
-        wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE,
-                    cachefiles_wait_bit, TASK_UNINTERRUPTIBLE);
-        _debug("<<< waited");
+        if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
+                wait_queue_head_t *wq;
+
+                signed long timeout = 60 * HZ;
+                wait_queue_t wait;
+                bool requeue;
+
+                /* if the object we're waiting for is queued for processing,
+                 * then just put ourselves on the queue behind it */
+                if (slow_work_is_queued(&xobject->fscache.work)) {
+                        _debug("queue OBJ%x behind OBJ%x immediately",
+                               object->fscache.debug_id,
+                               xobject->fscache.debug_id);
+                        goto requeue;
+                }
+
+                /* otherwise we sleep until either the object we're waiting for
+                 * is done, or the slow-work facility wants the thread back to
+                 * do other work */
+                wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
+                init_wait(&wait);
+                requeue = false;
+                do {
+                        prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
+                        if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
+                                break;
+                        requeue = slow_work_sleep_till_thread_needed(
+                                &object->fscache.work, &timeout);
+                } while (timeout > 0 && !requeue);
+                finish_wait(wq, &wait);
+
+                if (requeue &&
+                    test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
+                        _debug("queue OBJ%x behind OBJ%x after wait",
+                               object->fscache.debug_id,
+                               xobject->fscache.debug_id);
+                        goto requeue;
+                }
+
+                if (timeout <= 0) {
+                        printk(KERN_ERR "\n");
+                        printk(KERN_ERR "CacheFiles: Error: Overlong"
+                               " wait for old active object to go away\n");
+                        cachefiles_printk_object(object, xobject);
+                        goto requeue;
+                }
+        }
+
+        ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 
         cache->cache.ops->put_object(&xobject->fscache);
         goto try_again;
+
+requeue:
+        clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
+        cache->cache.ops->put_object(&xobject->fscache);
+        _leave(" = -ETIMEDOUT");
+        return -ETIMEDOUT;
 }
 
 /*
@@ -254,7 +347,7 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
 
         dir = dget_parent(object->dentry);
 
-        mutex_lock(&dir->d_inode->i_mutex);
+        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
         ret = cachefiles_bury_object(cache, dir, object->dentry);
 
         dput(dir);
@@ -307,7 +400,7 @@ lookup_again:
         /* search the current directory for the element name */
         _debug("lookup '%s'", name);
 
-        mutex_lock(&dir->d_inode->i_mutex);
+        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 
         start = jiffies;
         next = lookup_one_len(name, dir, nlen);
@@ -418,12 +511,15 @@ lookup_again:
         }
 
         /* note that we're now using this object */
-        cachefiles_mark_object_active(cache, object);
+        ret = cachefiles_mark_object_active(cache, object);
 
         mutex_unlock(&dir->d_inode->i_mutex);
         dput(dir);
         dir = NULL;
 
+        if (ret == -ETIMEDOUT)
+                goto mark_active_timed_out;
+
         _debug("=== OBTAINED_OBJECT ===");
 
         if (object->new) {
@@ -467,6 +563,10 @@ create_error:
                 cachefiles_io_error(cache, "Create/mkdir failed");
         goto error;
 
+mark_active_timed_out:
+        _debug("mark active timed out");
+        goto release_dentry;
+
 check_error:
         _debug("check error %d", ret);
         write_lock(&cache->active_lock);
@@ -474,7 +574,7 @@ check_error:
         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
         write_unlock(&cache->active_lock);
-
+release_dentry:
         dput(object->dentry);
         object->dentry = NULL;
         goto error_out;
@@ -495,9 +595,6 @@ error:
 error_out2:
         dput(dir);
 error_out:
-        if (ret == -ENOSPC)
-                ret = -ENOBUFS;
-
         _leave(" = error %d", -ret);
         return ret;
 }
diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
index a69787e7dd96..a6c8c6fe8df9 100644
--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -11,6 +11,7 @@
 
 #include <linux/mount.h>
 #include <linux/file.h>
+#include <linux/ima.h>
 #include "internal.h"
 
 /*
@@ -40,8 +41,10 @@ static int cachefiles_read_waiter(wait_queue_t *wait, unsigned mode,
 
         _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);
@@ -61,6 +64,84 @@ static int cachefiles_read_waiter(wait_queue_t *wait, unsigned mode,
 }
 
 /*
+ * 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
  */
@@ -92,20 +173,26 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
 
                 _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);
 
@@ -114,6 +201,7 @@ static void cachefiles_read_copier(struct fscache_operation *_op)
                 fscache_put_retrieval(op);
                 kfree(monitor);
 
+        next:
                 /* let the thread pool have some air occasionally */
                 max--;
                 if (max < 0 || need_resched()) {
@@ -333,7 +421,8 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
 
         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);
@@ -639,7 +728,8 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
 
         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);
@@ -801,7 +891,8 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
         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;
 
@@ -832,18 +923,33 @@ int cachefiles_write_page(struct fscache_storage *op, struct page *page)
         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);