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, 739 insertions, 0 deletions

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
new file mode 100644
index 000000000..e17bbc759
--- /dev/null
+++ b/fs/ext2/dir.c
@@ -0,0 +1,739 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/ext2/dir.c
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/fs/minix/dir.c
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ *  ext2 directory handling functions
+ *
+ *  Big-endian to little-endian byte-swapping/bitmaps by
+ *        David S. Miller (davem@caip.rutgers.edu), 1995
+ *
+ * All code that works with directory layout had been switched to pagecache
+ * and moved here. AV
+ */
+
+#include "ext2.h"
+#include <linux/buffer_head.h>
+#include <linux/filelock.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/iversion.h>
+
+typedef struct ext2_dir_entry_2 ext2_dirent;
+
+/*
+ * Tests against MAX_REC_LEN etc were put in place for 64k block
+ * sizes; if that is not possible on this arch, we can skip
+ * those tests and speed things up.
+ */
+static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
+{
+	unsigned len = le16_to_cpu(dlen);
+
+#if (PAGE_SIZE >= 65536)
+	if (len == EXT2_MAX_REC_LEN)
+		return 1 << 16;
+#endif
+	return len;
+}
+
+static inline __le16 ext2_rec_len_to_disk(unsigned len)
+{
+#if (PAGE_SIZE >= 65536)
+	if (len == (1 << 16))
+		return cpu_to_le16(EXT2_MAX_REC_LEN);
+	else
+		BUG_ON(len > (1 << 16));
+#endif
+	return cpu_to_le16(len);
+}
+
+/*
+ * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
+ * more robust, but we have what we have
+ */
+static inline unsigned ext2_chunk_size(struct inode *inode)
+{
+	return inode->i_sb->s_blocksize;
+}
+
+/*
+ * Return the offset into page `page_nr' of the last valid
+ * byte in that page, plus one.
+ */
+static unsigned
+ext2_last_byte(struct inode *inode, unsigned long page_nr)
+{
+	unsigned last_byte = inode->i_size;
+
+	last_byte -= page_nr << PAGE_SHIFT;
+	if (last_byte > PAGE_SIZE)
+		last_byte = PAGE_SIZE;
+	return last_byte;
+}
+
+static void ext2_commit_chunk(struct folio *folio, loff_t pos, unsigned len)
+{
+	struct address_space *mapping = folio->mapping;
+	struct inode *dir = mapping->host;
+
+	inode_inc_iversion(dir);
+	block_write_end(pos, len, len, folio);
+
+	if (pos+len > dir->i_size) {
+		i_size_write(dir, pos+len);
+		mark_inode_dirty(dir);
+	}
+	folio_unlock(folio);
+}
+
+static bool ext2_check_folio(struct folio *folio, int quiet, char *kaddr)
+{
+	struct inode *dir = folio->mapping->host;
+	struct super_block *sb = dir->i_sb;
+	unsigned chunk_size = ext2_chunk_size(dir);
+	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
+	unsigned offs, rec_len;
+	unsigned limit = folio_size(folio);
+	ext2_dirent *p;
+	char *error;
+
+	if (dir->i_size < folio_pos(folio) + limit) {
+		limit = offset_in_folio(folio, dir->i_size);
+		if (limit & (chunk_size - 1))
+			goto Ebadsize;
+		if (!limit)
+			goto out;
+	}
+	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
+		p = (ext2_dirent *)(kaddr + offs);
+		rec_len = ext2_rec_len_from_disk(p->rec_len);
+
+		if (unlikely(rec_len < EXT2_DIR_REC_LEN(1)))
+			goto Eshort;
+		if (unlikely(rec_len & 3))
+			goto Ealign;
+		if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len)))
+			goto Enamelen;
+		if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1)))
+			goto Espan;
+		if (unlikely(le32_to_cpu(p->inode) > max_inumber))
+			goto Einumber;
+	}
+	if (offs != limit)
+		goto Eend;
+out:
+	folio_set_checked(folio);
+	return true;
+
+	/* Too bad, we had an error */
+
+Ebadsize:
+	if (!quiet)
+		ext2_error(sb, __func__,
+			"size of directory #%llu is not a multiple "
+			"of chunk size", dir->i_ino);
+	goto fail;
+Eshort:
+	error = "rec_len is smaller than minimal";
+	goto bad_entry;
+Ealign:
+	error = "unaligned directory entry";
+	goto bad_entry;
+Enamelen:
+	error = "rec_len is too small for name_len";
+	goto bad_entry;
+Espan:
+	error = "directory entry across blocks";
+	goto bad_entry;
+Einumber:
+	error = "inode out of bounds";
+bad_entry:
+	if (!quiet)
+		ext2_error(sb, __func__, "bad entry in directory #%llu: : %s - "
+			"offset=%llu, inode=%lu, rec_len=%d, name_len=%d",
+			dir->i_ino, error, folio_pos(folio) + offs,
+			(unsigned long) le32_to_cpu(p->inode),
+			rec_len, p->name_len);
+	goto fail;
+Eend:
+	if (!quiet) {
+		p = (ext2_dirent *)(kaddr + offs);
+		ext2_error(sb, "ext2_check_folio",
+			"entry in directory #%llu spans the page boundary"
+			"offset=%llu, inode=%lu",
+			dir->i_ino, folio_pos(folio) + offs,
+			(unsigned long) le32_to_cpu(p->inode));
+	}
+fail:
+	return false;
+}
+
+/*
+ * Calls to ext2_get_folio()/folio_release_kmap() must be nested according
+ * to the rules documented in kmap_local_folio()/kunmap_local().
+ *
+ * NOTE: ext2_find_entry() and ext2_dotdot() act as a call
+ * to folio_release_kmap() and should be treated as a call to
+ * folio_release_kmap() for nesting purposes.
+ */
+static void *ext2_get_folio(struct inode *dir, unsigned long n,
+				   int quiet, struct folio **foliop)
+{
+	struct address_space *mapping = dir->i_mapping;
+	struct folio *folio = read_mapping_folio(mapping, n, NULL);
+	void *kaddr;
+
+	if (IS_ERR(folio))
+		return ERR_CAST(folio);
+	kaddr = kmap_local_folio(folio, 0);
+	if (unlikely(!folio_test_checked(folio))) {
+		if (!ext2_check_folio(folio, quiet, kaddr))
+			goto fail;
+	}
+	*foliop = folio;
+	return kaddr;
+
+fail:
+	folio_release_kmap(folio, kaddr);
+	return ERR_PTR(-EIO);
+}
+
+/*
+ * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
+ *
+ * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
+ */
+static inline int ext2_match (int len, const char * const name,
+					struct ext2_dir_entry_2 * de)
+{
+	if (len != de->name_len)
+		return 0;
+	if (!de->inode)
+		return 0;
+	return !memcmp(name, de->name, len);
+}
+
+/*
+ * p is at least 6 bytes before the end of page
+ */
+static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
+{
+	return (ext2_dirent *)((char *)p +
+			ext2_rec_len_from_disk(p->rec_len));
+}
+
+static inline unsigned 
+ext2_validate_entry(char *base, unsigned offset, unsigned mask)
+{
+	ext2_dirent *de = (ext2_dirent*)(base + offset);
+	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
+	while ((char*)p < (char*)de) {
+		if (p->rec_len == 0)
+			break;
+		p = ext2_next_entry(p);
+	}
+	return offset_in_page(p);
+}
+
+static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
+{
+	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
+		de->file_type = fs_umode_to_ftype(inode->i_mode);
+	else
+		de->file_type = 0;
+}
+
+static int
+ext2_readdir(struct file *file, struct dir_context *ctx)
+{
+	loff_t pos = ctx->pos;
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	unsigned int offset = pos & ~PAGE_MASK;
+	unsigned long n = pos >> PAGE_SHIFT;
+	unsigned long npages = dir_pages(inode);
+	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
+	bool need_revalidate = !inode_eq_iversion(inode, *(u64 *)file->private_data);
+	bool has_filetype;
+
+	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
+		return 0;
+
+	has_filetype =
+		EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE);
+
+	for ( ; n < npages; n++, offset = 0) {
+		ext2_dirent *de;
+		struct folio *folio;
+		char *kaddr = ext2_get_folio(inode, n, 0, &folio);
+		char *limit;
+
+		if (IS_ERR(kaddr)) {
+			ext2_error(sb, __func__,
+				   "bad page in #%llu",
+				   inode->i_ino);
+			ctx->pos += PAGE_SIZE - offset;
+			return PTR_ERR(kaddr);
+		}
+		if (unlikely(need_revalidate)) {
+			if (offset) {
+				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
+				ctx->pos = (n<<PAGE_SHIFT) + offset;
+			}
+			*(u64 *)file->private_data = inode_query_iversion(inode);
+			need_revalidate = false;
+		}
+		de = (ext2_dirent *)(kaddr+offset);
+		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
+		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
+			if (de->rec_len == 0) {
+				ext2_error(sb, __func__,
+					"zero-length directory entry");
+				folio_release_kmap(folio, de);
+				return -EIO;
+			}
+			if (de->inode) {
+				unsigned char d_type = DT_UNKNOWN;
+
+				if (has_filetype)
+					d_type = fs_ftype_to_dtype(de->file_type);
+
+				if (!dir_emit(ctx, de->name, de->name_len,
+						le32_to_cpu(de->inode),
+						d_type)) {
+					folio_release_kmap(folio, de);
+					return 0;
+				}
+			}
+			ctx->pos += ext2_rec_len_from_disk(de->rec_len);
+		}
+		folio_release_kmap(folio, kaddr);
+	}
+	return 0;
+}
+
+/*
+ *	ext2_find_entry()
+ *
+ * finds an entry in the specified directory with the wanted name. It
+ * returns the page in which the entry was found (as a parameter - res_page),
+ * and the entry itself. Page is returned mapped and unlocked.
+ * Entry is guaranteed to be valid.
+ *
+ * On Success folio_release_kmap() should be called on *foliop.
+ *
+ * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
+ * according to the rules documented in kmap_local_folio()/kunmap_local().
+ *
+ * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
+ * and should be treated as a call to ext2_get_folio() for nesting
+ * purposes.
+ */
+struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir,
+			const struct qstr *child, struct folio **foliop)
+{
+	const char *name = child->name;
+	int namelen = child->len;
+	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+	unsigned long start, n;
+	unsigned long npages = dir_pages(dir);
+	struct ext2_inode_info *ei = EXT2_I(dir);
+	ext2_dirent * de;
+
+	if (npages == 0)
+		goto out;
+
+	start = ei->i_dir_start_lookup;
+	if (start >= npages)
+		start = 0;
+	n = start;
+	do {
+		char *kaddr = ext2_get_folio(dir, n, 0, foliop);
+		if (IS_ERR(kaddr))
+			return ERR_CAST(kaddr);
+
+		de = (ext2_dirent *) kaddr;
+		kaddr += ext2_last_byte(dir, n) - reclen;
+		while ((char *) de <= kaddr) {
+			if (de->rec_len == 0) {
+				ext2_error(dir->i_sb, __func__,
+					"zero-length directory entry");
+				folio_release_kmap(*foliop, de);
+				goto out;
+			}
+			if (ext2_match(namelen, name, de))
+				goto found;
+			de = ext2_next_entry(de);
+		}
+		folio_release_kmap(*foliop, kaddr);
+
+		if (++n >= npages)
+			n = 0;
+		/* next folio is past the blocks we've got */
+		if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) {
+			ext2_error(dir->i_sb, __func__,
+				"dir %llu size %lld exceeds block count %llu",
+				dir->i_ino, dir->i_size,
+				(unsigned long long)dir->i_blocks);
+			goto out;
+		}
+	} while (n != start);
+out:
+	return ERR_PTR(-ENOENT);
+
+found:
+	ei->i_dir_start_lookup = n;
+	return de;
+}
+
+/*
+ * Return the '..' directory entry and the page in which the entry was found
+ * (as a parameter - p).
+ *
+ * On Success folio_release_kmap() should be called on *foliop.
+ *
+ * NOTE: Calls to ext2_get_folio()/folio_release_kmap() must be nested
+ * according to the rules documented in kmap_local_folio()/kunmap_local().
+ *
+ * ext2_find_entry() and ext2_dotdot() act as a call to ext2_get_folio()
+ * and should be treated as a call to ext2_get_folio() for nesting
+ * purposes.
+ */
+struct ext2_dir_entry_2 *ext2_dotdot(struct inode *dir, struct folio **foliop)
+{
+	ext2_dirent *de = ext2_get_folio(dir, 0, 0, foliop);
+
+	if (!IS_ERR(de))
+		return ext2_next_entry(de);
+	return NULL;
+}
+
+int ext2_inode_by_name(struct inode *dir, const struct qstr *child, ino_t *ino)
+{
+	struct ext2_dir_entry_2 *de;
+	struct folio *folio;
+
+	de = ext2_find_entry(dir, child, &folio);
+	if (IS_ERR(de))
+		return PTR_ERR(de);
+
+	*ino = le32_to_cpu(de->inode);
+	folio_release_kmap(folio, de);
+	return 0;
+}
+
+static int ext2_prepare_chunk(struct folio *folio, loff_t pos, unsigned len)
+{
+	return __block_write_begin(folio, pos, len, ext2_get_block);
+}
+
+static int ext2_handle_dirsync(struct inode *dir)
+{
+	int err;
+
+	err = filemap_write_and_wait(dir->i_mapping);
+	if (!err)
+		err = sync_inode_metadata(dir, 1);
+	return err;
+}
+
+int ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
+		struct folio *folio, struct inode *inode, bool update_times)
+{
+	loff_t pos = folio_pos(folio) + offset_in_folio(folio, de);
+	unsigned len = ext2_rec_len_from_disk(de->rec_len);
+	int err;
+
+	folio_lock(folio);
+	err = ext2_prepare_chunk(folio, pos, len);
+	if (err) {
+		folio_unlock(folio);
+		return err;
+	}
+	de->inode = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type(de, inode);
+	ext2_commit_chunk(folio, pos, len);
+	if (update_times)
+		inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
+	mark_inode_dirty(dir);
+	return ext2_handle_dirsync(dir);
+}
+
+/*
+ *	Parent is locked.
+ */
+int ext2_add_link (struct dentry *dentry, struct inode *inode)
+{
+	struct inode *dir = d_inode(dentry->d_parent);
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned chunk_size = ext2_chunk_size(dir);
+	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
+	unsigned short rec_len, name_len;
+	struct folio *folio = NULL;
+	ext2_dirent * de;
+	unsigned long npages = dir_pages(dir);
+	unsigned long n;
+	loff_t pos;
+	int err;
+
+	/*
+	 * We take care of directory expansion in the same loop.
+	 * This code plays outside i_size, so it locks the folio
+	 * to protect that region.
+	 */
+	for (n = 0; n <= npages; n++) {
+		char *kaddr = ext2_get_folio(dir, n, 0, &folio);
+		char *dir_end;
+
+		if (IS_ERR(kaddr))
+			return PTR_ERR(kaddr);
+		folio_lock(folio);
+		dir_end = kaddr + ext2_last_byte(dir, n);
+		de = (ext2_dirent *)kaddr;
+		kaddr += folio_size(folio) - reclen;
+		while ((char *)de <= kaddr) {
+			if ((char *)de == dir_end) {
+				/* We hit i_size */
+				name_len = 0;
+				rec_len = chunk_size;
+				de->rec_len = ext2_rec_len_to_disk(chunk_size);
+				de->inode = 0;
+				goto got_it;
+			}
+			if (de->rec_len == 0) {
+				ext2_error(dir->i_sb, __func__,
+					"zero-length directory entry");
+				err = -EIO;
+				goto out_unlock;
+			}
+			err = -EEXIST;
+			if (ext2_match (namelen, name, de))
+				goto out_unlock;
+			name_len = EXT2_DIR_REC_LEN(de->name_len);
+			rec_len = ext2_rec_len_from_disk(de->rec_len);
+			if (!de->inode && rec_len >= reclen)
+				goto got_it;
+			if (rec_len >= name_len + reclen)
+				goto got_it;
+			de = (ext2_dirent *) ((char *) de + rec_len);
+		}
+		folio_unlock(folio);
+		folio_release_kmap(folio, kaddr);
+	}
+	BUG();
+	return -EINVAL;
+
+got_it:
+	pos = folio_pos(folio) + offset_in_folio(folio, de);
+	err = ext2_prepare_chunk(folio, pos, rec_len);
+	if (err)
+		goto out_unlock;
+	if (de->inode) {
+		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
+		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
+		de->rec_len = ext2_rec_len_to_disk(name_len);
+		de = de1;
+	}
+	de->name_len = namelen;
+	memcpy(de->name, name, namelen);
+	de->inode = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type (de, inode);
+	ext2_commit_chunk(folio, pos, rec_len);
+	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
+	mark_inode_dirty(dir);
+	err = ext2_handle_dirsync(dir);
+	/* OFFSET_CACHE */
+out_put:
+	folio_release_kmap(folio, de);
+	return err;
+out_unlock:
+	folio_unlock(folio);
+	goto out_put;
+}
+
+/*
+ * ext2_delete_entry deletes a directory entry by merging it with the
+ * previous entry. Page is up-to-date.
+ */
+int ext2_delete_entry(struct ext2_dir_entry_2 *dir, struct folio *folio)
+{
+	struct inode *inode = folio->mapping->host;
+	size_t from, to;
+	char *kaddr;
+	loff_t pos;
+	ext2_dirent *de, *pde = NULL;
+	int err;
+
+	from = offset_in_folio(folio, dir);
+	to = from + ext2_rec_len_from_disk(dir->rec_len);
+	kaddr = (char *)dir - from;
+	from &= ~(ext2_chunk_size(inode)-1);
+	de = (ext2_dirent *)(kaddr + from);
+
+	while ((char*)de < (char*)dir) {
+		if (de->rec_len == 0) {
+			ext2_error(inode->i_sb, __func__,
+				"zero-length directory entry");
+			return -EIO;
+		}
+		pde = de;
+		de = ext2_next_entry(de);
+	}
+	if (pde)
+		from = offset_in_folio(folio, pde);
+	pos = folio_pos(folio) + from;
+	folio_lock(folio);
+	err = ext2_prepare_chunk(folio, pos, to - from);
+	if (err) {
+		folio_unlock(folio);
+		return err;
+	}
+	if (pde)
+		pde->rec_len = ext2_rec_len_to_disk(to - from);
+	dir->inode = 0;
+	ext2_commit_chunk(folio, pos, to - from);
+	inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
+	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
+	mark_inode_dirty(inode);
+	return ext2_handle_dirsync(inode);
+}
+
+/*
+ * Set the first fragment of directory.
+ */
+int ext2_make_empty(struct inode *inode, struct inode *parent)
+{
+	struct folio *folio = filemap_grab_folio(inode->i_mapping, 0);
+	unsigned chunk_size = ext2_chunk_size(inode);
+	struct ext2_dir_entry_2 * de;
+	int err;
+	void *kaddr;
+
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
+
+	err = ext2_prepare_chunk(folio, 0, chunk_size);
+	if (err) {
+		folio_unlock(folio);
+		goto fail;
+	}
+	kaddr = kmap_local_folio(folio, 0);
+	memset(kaddr, 0, chunk_size);
+	de = (struct ext2_dir_entry_2 *)kaddr;
+	de->name_len = 1;
+	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
+	memcpy (de->name, ".\0\0", 4);
+	de->inode = cpu_to_le32(inode->i_ino);
+	ext2_set_de_type (de, inode);
+
+	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
+	de->name_len = 2;
+	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
+	de->inode = cpu_to_le32(parent->i_ino);
+	memcpy (de->name, "..\0", 4);
+	ext2_set_de_type (de, inode);
+	kunmap_local(kaddr);
+	ext2_commit_chunk(folio, 0, chunk_size);
+	err = ext2_handle_dirsync(inode);
+fail:
+	folio_put(folio);
+	return err;
+}
+
+/*
+ * routine to check that the specified directory is empty (for rmdir)
+ */
+int ext2_empty_dir(struct inode *inode)
+{
+	struct folio *folio;
+	char *kaddr;
+	unsigned long i, npages = dir_pages(inode);
+
+	for (i = 0; i < npages; i++) {
+		ext2_dirent *de;
+
+		kaddr = ext2_get_folio(inode, i, 0, &folio);
+		if (IS_ERR(kaddr))
+			return 0;
+
+		de = (ext2_dirent *)kaddr;
+		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
+
+		while ((char *)de <= kaddr) {
+			if (de->rec_len == 0) {
+				ext2_error(inode->i_sb, __func__,
+					"zero-length directory entry");
+				printk("kaddr=%p, de=%p\n", kaddr, de);
+				goto not_empty;
+			}
+			if (de->inode != 0) {
+				/* check for . and .. */
+				if (de->name[0] != '.')
+					goto not_empty;
+				if (de->name_len > 2)
+					goto not_empty;
+				if (de->name_len < 2) {
+					if (de->inode !=
+					    cpu_to_le32(inode->i_ino))
+						goto not_empty;
+				} else if (de->name[1] != '.')
+					goto not_empty;
+			}
+			de = ext2_next_entry(de);
+		}
+		folio_release_kmap(folio, kaddr);
+	}
+	return 1;
+
+not_empty:
+	folio_release_kmap(folio, kaddr);
+	return 0;
+}
+
+static int ext2_dir_open(struct inode *inode, struct file *file)
+{
+	file->private_data = kzalloc(sizeof(u64), GFP_KERNEL);
+	if (!file->private_data)
+		return -ENOMEM;
+	return 0;
+}
+
+static int ext2_dir_release(struct inode *inode, struct file *file)
+{
+	kfree(file->private_data);
+	return 0;
+}
+
+static loff_t ext2_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+	return generic_llseek_cookie(file, offset, whence,
+				     (u64 *)file->private_data);
+}
+
+const struct file_operations ext2_dir_operations = {
+	.open		= ext2_dir_open,
+	.release	= ext2_dir_release,
+	.llseek		= ext2_dir_llseek,
+	.read		= generic_read_dir,
+	.iterate_shared	= ext2_readdir,
+	.unlocked_ioctl = ext2_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= ext2_compat_ioctl,
+#endif
+	.fsync		= simple_fsync,
+	.setlease	= generic_setlease,
+};