Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 557 insertions, 0 deletions

diff --git a/fs/squashfs/cache.c b/fs/squashfs/cache.c
new file mode 100644
index 000000000..c1a83bb0e
--- /dev/null
+++ b/fs/squashfs/cache.c
@@ -0,0 +1,557 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * cache.c
+ */
+
+/*
+ * Blocks in Squashfs are compressed.  To avoid repeatedly decompressing
+ * recently accessed data Squashfs uses two small metadata and fragment caches.
+ *
+ * This file implements a generic cache implementation used for both caches,
+ * plus functions layered ontop of the generic cache implementation to
+ * access the metadata and fragment caches.
+ *
+ * To avoid out of memory and fragmentation issues with vmalloc the cache
+ * uses sequences of kmalloced PAGE_SIZE buffers.
+ *
+ * It should be noted that the cache is not used for file datablocks, these
+ * are decompressed and cached in the page-cache in the normal way.  The
+ * cache is only used to temporarily cache fragment and metadata blocks
+ * which have been read as as a result of a metadata (i.e. inode or
+ * directory) or fragment access.  Because metadata and fragments are packed
+ * together into blocks (to gain greater compression) the read of a particular
+ * piece of metadata or fragment will retrieve other metadata/fragments which
+ * have been packed with it, these because of locality-of-reference may be read
+ * in the near future. Temporarily caching them ensures they are available for
+ * near future access without requiring an additional read and decompress.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/pagemap.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs.h"
+#include "page_actor.h"
+
+/*
+ * Waiters on cache->wait_queue are keyed by the block they want, so a wakeup
+ * can name who it is for.  A NULL key is a capacity wakeup: one entry became
+ * free, so wake one waiter.  A block key is a publication wakeup: that block
+ * now has an entry, so wake every waiter which can share it.
+ */
+struct squashfs_cache_wait {
+	wait_queue_entry_t	wait;
+	u64			block;
+	bool			capacity_wake;
+};
+
+static int squashfs_cache_wake_function(wait_queue_entry_t *wait,
+					unsigned int mode, int sync, void *key)
+{
+	struct squashfs_cache_wait *cache_wait =
+		container_of(wait, struct squashfs_cache_wait, wait);
+	u64 *block = key;
+
+	if (block && cache_wait->block != *block)
+		return 0;
+
+	WRITE_ONCE(cache_wait->capacity_wake, !block);
+
+	/*
+	 * Wake and unlink unconditionally instead of using
+	 * autoremove_wake_function(), which unlinks only when it changed the
+	 * task state.  A waiter can be made runnable by something which does
+	 * not go through this queue: wake_up_process() takes TASK_NORMAL, and
+	 * a cgroup v2 thaw calls it on every task in the cgroup, as do
+	 * free_pid() on a pid namespace init and a late rcuwait_wake_up().
+	 * try_to_wake_up() then fails.  Leaving such a waiter queued with a
+	 * reason already recorded would let it act on a freed entry it was not
+	 * given, and the failure would not consume the exclusive budget, so a
+	 * second waiter would be woken for the same entry.
+	 *
+	 * list_del_init_careful() must be the last access to @cache_wait: it
+	 * releases the waiter, whose wait structure lives on its stack, and it
+	 * pairs with list_empty_careful() in finish_wait() to publish the
+	 * store above.  __wake_up_common() samples ->flags and the next entry
+	 * before calling here, so it does not touch @wait afterwards either.
+	 */
+	default_wake_function(wait, mode, sync, key);
+	list_del_init_careful(&wait->entry);
+
+	return 1;
+}
+
+static void squashfs_cache_wake_block(struct squashfs_cache *cache, u64 block)
+{
+	/* nr_exclusive == 0: wake every waiter which matches the key. */
+	__wake_up(&cache->wait_queue, TASK_NORMAL, 0, &block);
+}
+
+/*
+ * Look-up block in cache, and increment usage count.  If not in cache, read
+ * and decompress it from disk.
+ *
+ * A caller which finds no free entry sleeps on cache->wait_queue as an
+ * exclusive waiter, so squashfs_cache_put() releasing one entry wakes exactly
+ * one task.  Because a wakee may find its block published in the meantime and
+ * share that entry rather than claim the free one, a wakee which shares hands
+ * its wakeup on to the next waiter.
+ */
+struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb,
+	struct squashfs_cache *cache, u64 block, int length)
+{
+	int i, n;
+	struct squashfs_cache_entry *entry;
+	bool capacity_wake = false;
+
+	spin_lock(&cache->lock);
+
+	while (1) {
+		bool pending, wake_next, wake_block;
+
+		for (i = cache->curr_blk, n = 0; n < cache->entries; n++) {
+			if (cache->entry[i].block == block) {
+				cache->curr_blk = i;
+				break;
+			}
+			i = (i + 1) % cache->entries;
+		}
+
+		if (n == cache->entries) {
+			/*
+			 * Block not in cache, if all cache entries are used
+			 * go to sleep waiting for one to become available.
+			 */
+			if (cache->unused == 0) {
+				struct squashfs_cache_wait wait = {
+					.block		= block,
+					.capacity_wake	= false,
+				};
+
+				init_wait_func(&wait.wait,
+					       squashfs_cache_wake_function);
+				cache->num_waiters++;
+				/*
+				 * Enqueue while still holding cache->lock, so
+				 * that a concurrent lookup either sees us
+				 * queued or we see the block it publishes.
+				 */
+				prepare_to_wait_exclusive(&cache->wait_queue,
+						&wait.wait, TASK_UNINTERRUPTIBLE);
+				spin_unlock(&cache->lock);
+				schedule();
+				finish_wait(&cache->wait_queue, &wait.wait);
+				capacity_wake = READ_ONCE(wait.capacity_wake);
+				spin_lock(&cache->lock);
+				cache->num_waiters--;
+				continue;
+			}
+
+			/*
+			 * At least one unused cache entry.  A simple
+			 * round-robin strategy is used to choose the entry to
+			 * be evicted from the cache.
+			 */
+			i = cache->next_blk;
+			for (n = 0; n < cache->entries; n++) {
+				if (cache->entry[i].refcount == 0)
+					break;
+				i = (i + 1) % cache->entries;
+			}
+
+			cache->next_blk = (i + 1) % cache->entries;
+			entry = &cache->entry[i];
+
+			/*
+			 * Initialise chosen cache entry, and fill it in from
+			 * disk.
+			 */
+			cache->unused--;
+			entry->block = block;
+			entry->refcount = 1;
+			entry->pending = 1;
+			entry->num_waiters = 0;
+			entry->error = 0;
+			wake_block = cache->num_waiters > 0;
+			spin_unlock(&cache->lock);
+
+			/*
+			 * The entry is now findable, so release everybody
+			 * queued for this block to share it rather than each
+			 * waiting for an entry of their own.  They will block
+			 * on entry->wait_queue below until the read completes.
+			 */
+			if (wake_block)
+				squashfs_cache_wake_block(cache, block);
+
+			entry->length = squashfs_read_data(sb, block, length,
+				&entry->next_index, entry->actor);
+
+			spin_lock(&cache->lock);
+
+			if (entry->length < 0)
+				entry->error = entry->length;
+
+			entry->pending = 0;
+
+			/*
+			 * While filling this entry one or more other processes
+			 * have looked it up in the cache, and have slept
+			 * waiting for it to become available.
+			 */
+			if (entry->num_waiters) {
+				spin_unlock(&cache->lock);
+				wake_up_all(&entry->wait_queue);
+			} else
+				spin_unlock(&cache->lock);
+
+			goto out;
+		}
+
+		/*
+		 * Block already in cache.  Increment refcount so it doesn't
+		 * get reused until we're finished with it, if it was
+		 * previously unused there's one less cache entry available
+		 * for reuse.
+		 */
+		entry = &cache->entry[i];
+		if (entry->refcount == 0) {
+			cache->unused--;
+			/* This claims the capacity we were woken for. */
+			capacity_wake = false;
+		}
+		entry->refcount++;
+
+		/*
+		 * If the entry is currently being filled in by another process
+		 * go to sleep waiting for it to become available.
+		 */
+		pending = entry->pending;
+		if (pending)
+			entry->num_waiters++;
+
+		/*
+		 * We were woken because an entry became free, but shared a
+		 * block instead of claiming it.  Hand the wakeup on, otherwise
+		 * the free entry sits unclaimed while others sleep.
+		 */
+		wake_next = capacity_wake && cache->unused && cache->num_waiters;
+		spin_unlock(&cache->lock);
+
+		if (wake_next)
+			wake_up(&cache->wait_queue);
+		if (pending)
+			wait_event(entry->wait_queue, !entry->pending);
+
+		goto out;
+	}
+
+out:
+	TRACE("Got %s %d, start block %lld, refcount %d, error %d\n",
+		cache->name, i, entry->block, entry->refcount, entry->error);
+
+	if (entry->error)
+		ERROR("Unable to read %s cache entry [%llx]\n", cache->name,
+							block);
+	return entry;
+}
+
+
+/*
+ * Release cache entry, once usage count is zero it can be reused.
+ */
+void squashfs_cache_put(struct squashfs_cache_entry *entry)
+{
+	struct squashfs_cache *cache = entry->cache;
+
+	spin_lock(&cache->lock);
+	entry->refcount--;
+	if (entry->refcount == 0) {
+		cache->unused++;
+		/*
+		 * If there's any processes waiting for a block to become
+		 * available, wake one up.
+		 */
+		if (cache->num_waiters) {
+			spin_unlock(&cache->lock);
+			wake_up(&cache->wait_queue);
+			return;
+		}
+	}
+	spin_unlock(&cache->lock);
+}
+
+/*
+ * Delete cache reclaiming all kmalloced buffers.
+ */
+void squashfs_cache_delete(struct squashfs_cache *cache)
+{
+	int i, j;
+
+	if (IS_ERR(cache) || cache == NULL)
+		return;
+
+	for (i = 0; i < cache->entries; i++) {
+		if (cache->entry[i].data) {
+			for (j = 0; j < cache->pages; j++)
+				kfree(cache->entry[i].data[j]);
+			kfree(cache->entry[i].data);
+		}
+		kfree(cache->entry[i].actor);
+	}
+
+	kfree(cache->entry);
+	kfree(cache);
+}
+
+
+/*
+ * Initialise cache allocating the specified number of entries, each of
+ * size block_size.  To avoid vmalloc fragmentation issues each entry
+ * is allocated as a sequence of kmalloced PAGE_SIZE buffers.
+ */
+struct squashfs_cache *squashfs_cache_init(char *name, int entries,
+	int block_size)
+{
+	int i, j;
+	struct squashfs_cache *cache;
+
+	if (entries == 0)
+		return NULL;
+
+	cache = kzalloc_obj(*cache);
+	if (cache == NULL) {
+		ERROR("Failed to allocate %s cache\n", name);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	cache->entry = kzalloc_objs(*(cache->entry), entries);
+	if (cache->entry == NULL) {
+		ERROR("Failed to allocate %s cache\n", name);
+		goto cleanup;
+	}
+
+	cache->curr_blk = 0;
+	cache->next_blk = 0;
+	cache->unused = entries;
+	cache->entries = entries;
+	cache->block_size = block_size;
+	cache->pages = block_size >> PAGE_SHIFT;
+	cache->pages = cache->pages ? cache->pages : 1;
+	cache->name = name;
+	cache->num_waiters = 0;
+	spin_lock_init(&cache->lock);
+	init_waitqueue_head(&cache->wait_queue);
+
+	for (i = 0; i < entries; i++) {
+		struct squashfs_cache_entry *entry = &cache->entry[i];
+
+		init_waitqueue_head(&cache->entry[i].wait_queue);
+		entry->cache = cache;
+		entry->block = SQUASHFS_INVALID_BLK;
+		entry->data = kcalloc(cache->pages, sizeof(void *), GFP_KERNEL);
+		if (entry->data == NULL) {
+			ERROR("Failed to allocate %s cache entry\n", name);
+			goto cleanup;
+		}
+
+		for (j = 0; j < cache->pages; j++) {
+			entry->data[j] = kmalloc(PAGE_SIZE, GFP_KERNEL);
+			if (entry->data[j] == NULL) {
+				ERROR("Failed to allocate %s buffer\n", name);
+				goto cleanup;
+			}
+		}
+
+		entry->actor = squashfs_page_actor_init(entry->data,
+						cache->pages, 0);
+		if (entry->actor == NULL) {
+			ERROR("Failed to allocate %s cache entry\n", name);
+			goto cleanup;
+		}
+	}
+
+	return cache;
+
+cleanup:
+	squashfs_cache_delete(cache);
+	return ERR_PTR(-ENOMEM);
+}
+
+
+/*
+ * Copy up to length bytes from cache entry to buffer starting at offset bytes
+ * into the cache entry.  If there's not length bytes then copy the number of
+ * bytes available.  In all cases return the number of bytes copied.
+ */
+int squashfs_copy_data(void *buffer, struct squashfs_cache_entry *entry,
+		int offset, int length)
+{
+	int remaining = length;
+
+	if (length == 0 || offset < 0)
+		return 0;
+	else if (buffer == NULL)
+		return min(length, entry->length - offset);
+
+	while (offset < entry->length) {
+		void *buff = entry->data[offset / PAGE_SIZE]
+				+ (offset % PAGE_SIZE);
+		int bytes = min_t(int, entry->length - offset,
+				PAGE_SIZE - (offset % PAGE_SIZE));
+
+		if (bytes >= remaining) {
+			memcpy(buffer, buff, remaining);
+			remaining = 0;
+			break;
+		}
+
+		memcpy(buffer, buff, bytes);
+		buffer += bytes;
+		remaining -= bytes;
+		offset += bytes;
+	}
+
+	return length - remaining;
+}
+
+
+/*
+ * Read length bytes from metadata position <block, offset> (block is the
+ * start of the compressed block on disk, and offset is the offset into
+ * the block once decompressed).  Data is packed into consecutive blocks,
+ * and length bytes may require reading more than one block.
+ */
+int squashfs_read_metadata(struct super_block *sb, void *buffer,
+		u64 *block, int *offset, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int bytes, res = length;
+	struct squashfs_cache_entry *entry;
+
+	TRACE("Entered squashfs_read_metadata [%llx:%x]\n", *block, *offset);
+
+	if (unlikely(length < 0))
+		return -EIO;
+
+	if (unlikely(*offset < 0 || *offset >= SQUASHFS_METADATA_SIZE))
+		return -EIO;
+
+	while (length) {
+		entry = squashfs_cache_get(sb, msblk->block_cache, *block, 0);
+		if (entry->error) {
+			res = entry->error;
+			goto error;
+		} else if (*offset >= entry->length) {
+			res = -EIO;
+			goto error;
+		}
+
+		bytes = squashfs_copy_data(buffer, entry, *offset, length);
+		if (buffer)
+			buffer += bytes;
+		length -= bytes;
+		*offset += bytes;
+
+		if (*offset == entry->length) {
+			*block = entry->next_index;
+			*offset = 0;
+		}
+
+		squashfs_cache_put(entry);
+	}
+
+	return res;
+
+error:
+	squashfs_cache_put(entry);
+	return res;
+}
+
+
+/*
+ * Look-up in the fragmment cache the fragment located at <start_block> in the
+ * filesystem.  If necessary read and decompress it from disk.
+ */
+struct squashfs_cache_entry *squashfs_get_fragment(struct super_block *sb,
+				u64 start_block, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+
+	return squashfs_cache_get(sb, msblk->fragment_cache, start_block,
+		length);
+}
+
+
+/*
+ * Read and decompress the datablock located at <start_block> in the
+ * filesystem.  The cache is used here to avoid duplicating locking and
+ * read/decompress code.
+ */
+struct squashfs_cache_entry *squashfs_get_datablock(struct super_block *sb,
+				u64 start_block, int length)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+
+	return squashfs_cache_get(sb, msblk->read_page, start_block, length);
+}
+
+
+/*
+ * Read a filesystem table (uncompressed sequence of bytes) from disk
+ */
+void *squashfs_read_table(struct super_block *sb, u64 block, int length)
+{
+	int pages = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	int i, res;
+	void *table, *buffer, **data;
+	struct squashfs_page_actor *actor;
+
+	table = buffer = kmalloc(length, GFP_KERNEL);
+	if (table == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	data = kcalloc(pages, sizeof(void *), GFP_KERNEL);
+	if (data == NULL) {
+		res = -ENOMEM;
+		goto failed;
+	}
+
+	actor = squashfs_page_actor_init(data, pages, length);
+	if (actor == NULL) {
+		res = -ENOMEM;
+		goto failed2;
+	}
+
+	for (i = 0; i < pages; i++, buffer += PAGE_SIZE)
+		data[i] = buffer;
+
+	res = squashfs_read_data(sb, block, length |
+		SQUASHFS_COMPRESSED_BIT_BLOCK, NULL, actor);
+
+	kfree(data);
+	kfree(actor);
+
+	if (res < 0)
+		goto failed;
+
+	return table;
+
+failed2:
+	kfree(data);
+failed:
+	kfree(table);
+	return ERR_PTR(res);
+}