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, 1030 insertions, 0 deletions

diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
new file mode 100644
index 000000000..ee0cbae52
--- /dev/null
+++ b/fs/befs/linuxvfs.c
@@ -0,0 +1,1030 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/befs/linuxvfs.c
+ *
+ * Copyright (C) 2001 Will Dyson <will_dyson@pobox.com
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
+#include <linux/errno.h>
+#include <linux/filelock.h>
+#include <linux/stat.h>
+#include <linux/nls.h>
+#include <linux/buffer_head.h>
+#include <linux/vfs.h>
+#include <linux/namei.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/exportfs.h>
+#include <linux/seq_file.h>
+#include <linux/blkdev.h>
+
+#include "befs.h"
+#include "btree.h"
+#include "inode.h"
+#include "datastream.h"
+#include "super.h"
+#include "io.h"
+
+MODULE_DESCRIPTION("BeOS File System (BeFS) driver");
+MODULE_AUTHOR("Will Dyson");
+MODULE_LICENSE("GPL");
+
+/* The units the vfs expects inode->i_blocks to be in */
+#define VFS_BLOCK_SIZE 512
+
+static int befs_readdir(struct file *, struct dir_context *);
+static int befs_get_block(struct inode *, sector_t, struct buffer_head *, int);
+static int befs_read_folio(struct file *file, struct folio *folio);
+static sector_t befs_bmap(struct address_space *mapping, sector_t block);
+static struct dentry *befs_lookup(struct inode *, struct dentry *,
+				  unsigned int);
+static struct inode *befs_iget(struct super_block *, unsigned long);
+static struct inode *befs_alloc_inode(struct super_block *sb);
+static void befs_free_inode(struct inode *inode);
+static void befs_destroy_inodecache(void);
+static int befs_symlink_read_folio(struct file *, struct folio *);
+static int befs_utf2nls(struct super_block *sb, const char *in, int in_len,
+			char **out, int *out_len);
+static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
+			char **out, int *out_len);
+static void befs_put_super(struct super_block *);
+static int befs_statfs(struct dentry *, struct kstatfs *);
+static int befs_show_options(struct seq_file *, struct dentry *);
+static struct dentry *befs_fh_to_dentry(struct super_block *sb,
+				struct fid *fid, int fh_len, int fh_type);
+static struct dentry *befs_fh_to_parent(struct super_block *sb,
+				struct fid *fid, int fh_len, int fh_type);
+static struct dentry *befs_get_parent(struct dentry *child);
+static void befs_free_fc(struct fs_context *fc);
+
+static const struct super_operations befs_sops = {
+	.alloc_inode	= befs_alloc_inode,	/* allocate a new inode */
+	.free_inode	= befs_free_inode, /* deallocate an inode */
+	.put_super	= befs_put_super,	/* uninit super */
+	.statfs		= befs_statfs,	/* statfs */
+	.show_options	= befs_show_options,
+};
+
+/* slab cache for befs_inode_info objects */
+static struct kmem_cache *befs_inode_cachep;
+
+static const struct file_operations befs_dir_operations = {
+	.read		= generic_read_dir,
+	.iterate_shared	= befs_readdir,
+	.llseek		= generic_file_llseek,
+	.setlease	= generic_setlease,
+};
+
+static const struct inode_operations befs_dir_inode_operations = {
+	.lookup		= befs_lookup,
+};
+
+static const struct address_space_operations befs_aops = {
+	.read_folio	= befs_read_folio,
+	.bmap		= befs_bmap,
+};
+
+static const struct address_space_operations befs_symlink_aops = {
+	.read_folio	= befs_symlink_read_folio,
+};
+
+static const struct export_operations befs_export_operations = {
+	.encode_fh	= generic_encode_ino32_fh,
+	.fh_to_dentry	= befs_fh_to_dentry,
+	.fh_to_parent	= befs_fh_to_parent,
+	.get_parent	= befs_get_parent,
+};
+
+/*
+ * Called by generic_file_read() to read a folio of data
+ *
+ * In turn, simply calls a generic block read function and
+ * passes it the address of befs_get_block, for mapping file
+ * positions to disk blocks.
+ */
+static int befs_read_folio(struct file *file, struct folio *folio)
+{
+	return block_read_full_folio(folio, befs_get_block);
+}
+
+static sector_t
+befs_bmap(struct address_space *mapping, sector_t block)
+{
+	return generic_block_bmap(mapping, block, befs_get_block);
+}
+
+/*
+ * Generic function to map a file position (block) to a
+ * disk offset (passed back in bh_result).
+ *
+ * Used by many higher level functions.
+ *
+ * Calls befs_fblock2brun() in datastream.c to do the real work.
+ */
+
+static int
+befs_get_block(struct inode *inode, sector_t block,
+	       struct buffer_head *bh_result, int create)
+{
+	struct super_block *sb = inode->i_sb;
+	befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
+	befs_block_run run = BAD_IADDR;
+	int res;
+	ulong disk_off;
+
+	befs_debug(sb, "---> befs_get_block() for inode %llu, block %ld",
+		   inode->i_ino, (long)block);
+	if (create) {
+		befs_error(sb, "befs_get_block() was asked to write to "
+			   "block %ld in inode %llu", (long)block,
+			   inode->i_ino);
+		return -EPERM;
+	}
+
+	res = befs_fblock2brun(sb, ds, block, &run);
+	if (res != BEFS_OK) {
+		befs_error(sb,
+			   "<--- %s for inode %llu, block %ld ERROR",
+			   __func__, inode->i_ino,
+			   (long)block);
+		return -EFBIG;
+	}
+
+	disk_off = (ulong) iaddr2blockno(sb, &run);
+
+	map_bh(bh_result, inode->i_sb, disk_off);
+
+	befs_debug(sb, "<--- %s for inode %llu, block %ld, disk address %lu",
+		  __func__, inode->i_ino, (long)block,
+		  (unsigned long)disk_off);
+
+	return 0;
+}
+
+static struct dentry *
+befs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
+{
+	struct inode *inode;
+	struct super_block *sb = dir->i_sb;
+	const befs_data_stream *ds = &BEFS_I(dir)->i_data.ds;
+	befs_off_t offset;
+	int ret;
+	int utfnamelen;
+	char *utfname;
+	const char *name = dentry->d_name.name;
+
+	befs_debug(sb, "---> %s name %pd inode %llu", __func__,
+		   dentry, dir->i_ino);
+
+	/* Convert to UTF-8 */
+	if (BEFS_SB(sb)->nls) {
+		ret =
+		    befs_nls2utf(sb, name, strlen(name), &utfname, &utfnamelen);
+		if (ret < 0) {
+			befs_debug(sb, "<--- %s ERROR", __func__);
+			return ERR_PTR(ret);
+		}
+		ret = befs_btree_find(sb, ds, utfname, &offset);
+		kfree(utfname);
+
+	} else {
+		ret = befs_btree_find(sb, ds, name, &offset);
+	}
+
+	if (ret == BEFS_BT_NOT_FOUND) {
+		befs_debug(sb, "<--- %s %pd not found", __func__, dentry);
+		inode = NULL;
+	} else if (ret != BEFS_OK || offset == 0) {
+		befs_error(sb, "<--- %s Error", __func__);
+		inode = ERR_PTR(-ENODATA);
+	} else {
+		inode = befs_iget(dir->i_sb, (ino_t) offset);
+	}
+	befs_debug(sb, "<--- %s", __func__);
+
+	return d_splice_alias(inode, dentry);
+}
+
+static int
+befs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	const befs_data_stream *ds = &BEFS_I(inode)->i_data.ds;
+	befs_off_t value;
+	int result;
+	size_t keysize;
+	char keybuf[BEFS_NAME_LEN + 1];
+
+	befs_debug(sb, "---> %s name %pD, inode %llu, ctx->pos %lld",
+		  __func__, file, inode->i_ino, ctx->pos);
+
+	while (1) {
+		result = befs_btree_read(sb, ds, ctx->pos, BEFS_NAME_LEN + 1,
+					 keybuf, &keysize, &value);
+
+		if (result == BEFS_ERR) {
+			befs_debug(sb, "<--- %s ERROR", __func__);
+			befs_error(sb, "IO error reading %pD (inode %llu)",
+				   file, inode->i_ino);
+			return -EIO;
+
+		} else if (result == BEFS_BT_END) {
+			befs_debug(sb, "<--- %s END", __func__);
+			return 0;
+
+		} else if (result == BEFS_BT_EMPTY) {
+			befs_debug(sb, "<--- %s Empty directory", __func__);
+			return 0;
+		}
+
+		/* Convert to NLS */
+		if (BEFS_SB(sb)->nls) {
+			char *nlsname;
+			int nlsnamelen;
+
+			result =
+			    befs_utf2nls(sb, keybuf, keysize, &nlsname,
+					 &nlsnamelen);
+			if (result < 0) {
+				befs_debug(sb, "<--- %s ERROR", __func__);
+				return result;
+			}
+			if (!dir_emit(ctx, nlsname, nlsnamelen,
+				      (ino_t) value, DT_UNKNOWN)) {
+				kfree(nlsname);
+				return 0;
+			}
+			kfree(nlsname);
+		} else {
+			if (!dir_emit(ctx, keybuf, keysize,
+				      (ino_t) value, DT_UNKNOWN))
+				return 0;
+		}
+		ctx->pos++;
+	}
+}
+
+static struct inode *
+befs_alloc_inode(struct super_block *sb)
+{
+	struct befs_inode_info *bi;
+
+	bi = alloc_inode_sb(sb, befs_inode_cachep, GFP_KERNEL);
+	if (!bi)
+		return NULL;
+	return &bi->vfs_inode;
+}
+
+static void befs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(befs_inode_cachep, BEFS_I(inode));
+}
+
+static void init_once(void *foo)
+{
+	struct befs_inode_info *bi = (struct befs_inode_info *) foo;
+
+	inode_init_once(&bi->vfs_inode);
+}
+
+static struct inode *befs_iget(struct super_block *sb, unsigned long ino)
+{
+	struct buffer_head *bh;
+	befs_inode *raw_inode;
+	struct befs_sb_info *befs_sb = BEFS_SB(sb);
+	struct befs_inode_info *befs_ino;
+	struct inode *inode;
+
+	befs_debug(sb, "---> %s inode = %lu", __func__, ino);
+
+	inode = iget_locked(sb, ino);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+	if (!(inode_state_read_once(inode) & I_NEW))
+		return inode;
+
+	befs_ino = BEFS_I(inode);
+
+	/* convert from vfs's inode number to befs's inode number */
+	befs_ino->i_inode_num = blockno2iaddr(sb, inode->i_ino);
+
+	befs_debug(sb, "  real inode number [%u, %hu, %hu]",
+		   befs_ino->i_inode_num.allocation_group,
+		   befs_ino->i_inode_num.start, befs_ino->i_inode_num.len);
+
+	bh = sb_bread(sb, inode->i_ino);
+	if (!bh) {
+		befs_error(sb, "unable to read inode block - "
+			   "inode = %llu", inode->i_ino);
+		goto unacquire_none;
+	}
+
+	raw_inode = (befs_inode *) bh->b_data;
+
+	befs_dump_inode(sb, raw_inode);
+
+	if (befs_check_inode(sb, raw_inode, inode->i_ino) != BEFS_OK) {
+		befs_error(sb, "Bad inode: %llu", inode->i_ino);
+		goto unacquire_bh;
+	}
+
+	inode->i_mode = (umode_t) fs32_to_cpu(sb, raw_inode->mode);
+
+	/*
+	 * set uid and gid.  But since current BeOS is single user OS, so
+	 * you can change by "uid" or "gid" options.
+	 */
+
+	inode->i_uid = befs_sb->mount_opts.use_uid ?
+		befs_sb->mount_opts.uid :
+		make_kuid(&init_user_ns, fs32_to_cpu(sb, raw_inode->uid));
+	inode->i_gid = befs_sb->mount_opts.use_gid ?
+		befs_sb->mount_opts.gid :
+		make_kgid(&init_user_ns, fs32_to_cpu(sb, raw_inode->gid));
+
+	set_nlink(inode, 1);
+
+	/*
+	 * BEFS's time is 64 bits, but current VFS is 32 bits...
+	 * BEFS don't have access time. Nor inode change time. VFS
+	 * doesn't have creation time.
+	 * Also, the lower 16 bits of the last_modified_time and
+	 * create_time are just a counter to help ensure uniqueness
+	 * for indexing purposes. (PFD, page 54)
+	 */
+
+	inode_set_mtime(inode,
+			fs64_to_cpu(sb, raw_inode->last_modified_time) >> 16,
+			0);/* lower 16 bits are not a time */
+	inode_set_ctime_to_ts(inode, inode_get_mtime(inode));
+	inode_set_atime_to_ts(inode, inode_get_mtime(inode));
+
+	befs_ino->i_inode_num = fsrun_to_cpu(sb, raw_inode->inode_num);
+	befs_ino->i_parent = fsrun_to_cpu(sb, raw_inode->parent);
+	befs_ino->i_attribute = fsrun_to_cpu(sb, raw_inode->attributes);
+	befs_ino->i_flags = fs32_to_cpu(sb, raw_inode->flags);
+
+	if (S_ISLNK(inode->i_mode) && !(befs_ino->i_flags & BEFS_LONG_SYMLINK)){
+		inode->i_size = 0;
+		inode->i_blocks = befs_sb->block_size / VFS_BLOCK_SIZE;
+		strscpy(befs_ino->i_data.symlink, raw_inode->data.symlink,
+			BEFS_SYMLINK_LEN);
+	} else {
+		int num_blks;
+
+		befs_ino->i_data.ds =
+		    fsds_to_cpu(sb, &raw_inode->data.datastream);
+
+		num_blks = befs_count_blocks(sb, &befs_ino->i_data.ds);
+		inode->i_blocks =
+		    num_blks * (befs_sb->block_size / VFS_BLOCK_SIZE);
+		inode->i_size = befs_ino->i_data.ds.size;
+	}
+
+	inode->i_mapping->a_ops = &befs_aops;
+
+	if (S_ISREG(inode->i_mode)) {
+		inode->i_fop = &generic_ro_fops;
+	} else if (S_ISDIR(inode->i_mode)) {
+		inode->i_op = &befs_dir_inode_operations;
+		inode->i_fop = &befs_dir_operations;
+	} else if (S_ISLNK(inode->i_mode)) {
+		if (befs_ino->i_flags & BEFS_LONG_SYMLINK) {
+			inode->i_op = &page_symlink_inode_operations;
+			inode_nohighmem(inode);
+			inode->i_mapping->a_ops = &befs_symlink_aops;
+		} else {
+			inode->i_link = befs_ino->i_data.symlink;
+			inode->i_op = &simple_symlink_inode_operations;
+		}
+	} else {
+		befs_error(sb, "Inode %llu is not a regular file, "
+			   "directory or symlink. THAT IS WRONG! BeFS has no "
+			   "on disk special files", inode->i_ino);
+		goto unacquire_bh;
+	}
+
+	brelse(bh);
+	befs_debug(sb, "<--- %s", __func__);
+	unlock_new_inode(inode);
+	return inode;
+
+unacquire_bh:
+	brelse(bh);
+
+unacquire_none:
+	iget_failed(inode);
+	befs_debug(sb, "<--- %s - Bad inode", __func__);
+	return ERR_PTR(-EIO);
+}
+
+/* Initialize the inode cache. Called at fs setup.
+ *
+ * Taken from NFS implementation by Al Viro.
+ */
+static int __init
+befs_init_inodecache(void)
+{
+	befs_inode_cachep = kmem_cache_create_usercopy("befs_inode_cache",
+				sizeof(struct befs_inode_info), 0,
+				SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
+				offsetof(struct befs_inode_info,
+					i_data.symlink),
+				sizeof_field(struct befs_inode_info,
+					i_data.symlink),
+				init_once);
+	if (befs_inode_cachep == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/* Called at fs teardown.
+ *
+ * Taken from NFS implementation by Al Viro.
+ */
+static void
+befs_destroy_inodecache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(befs_inode_cachep);
+}
+
+/*
+ * The inode of symbolic link is different to data stream.
+ * The data stream become link name. Unless the LONG_SYMLINK
+ * flag is set.
+ */
+static int befs_symlink_read_folio(struct file *unused, struct folio *folio)
+{
+	struct inode *inode = folio->mapping->host;
+	struct super_block *sb = inode->i_sb;
+	struct befs_inode_info *befs_ino = BEFS_I(inode);
+	befs_data_stream *data = &befs_ino->i_data.ds;
+	befs_off_t len = data->size;
+	char *link = folio_address(folio);
+	int err = -EIO;
+
+	if (len == 0 || len > PAGE_SIZE) {
+		befs_error(sb, "Long symlink with illegal length");
+		goto fail;
+	}
+	befs_debug(sb, "Follow long symlink");
+
+	if (befs_read_lsymlink(sb, data, link, len) != len) {
+		befs_error(sb, "Failed to read entire long symlink");
+		goto fail;
+	}
+	link[len - 1] = '\0';
+	err = 0;
+fail:
+	folio_end_read(folio, err == 0);
+	return err;
+}
+
+/*
+ * UTF-8 to NLS charset convert routine
+ *
+ * Uses uni2char() / char2uni() rather than the nls tables directly
+ */
+static int
+befs_utf2nls(struct super_block *sb, const char *in,
+	     int in_len, char **out, int *out_len)
+{
+	struct nls_table *nls = BEFS_SB(sb)->nls;
+	int i, o;
+	unicode_t uni;
+	int unilen, utflen;
+	char *result;
+	/* The utf8->nls conversion won't make the final nls string bigger
+	 * than the utf one, but if the string is pure ascii they'll have the
+	 * same width and an extra char is needed to save the additional \0
+	 */
+	int maxlen = in_len + 1;
+
+	befs_debug(sb, "---> %s", __func__);
+
+	if (!nls) {
+		befs_error(sb, "%s called with no NLS table loaded", __func__);
+		return -EINVAL;
+	}
+
+	*out = result = kmalloc(maxlen, GFP_NOFS);
+	if (!*out)
+		return -ENOMEM;
+
+	for (i = o = 0; i < in_len; i += utflen, o += unilen) {
+
+		/* convert from UTF-8 to Unicode */
+		utflen = utf8_to_utf32(&in[i], in_len - i, &uni);
+		if (utflen < 0)
+			goto conv_err;
+
+		/* convert from Unicode to nls */
+		if (uni > MAX_WCHAR_T)
+			goto conv_err;
+		unilen = nls->uni2char(uni, &result[o], in_len - o);
+		if (unilen < 0)
+			goto conv_err;
+	}
+	result[o] = '\0';
+	*out_len = o;
+
+	befs_debug(sb, "<--- %s", __func__);
+
+	return o;
+
+conv_err:
+	befs_error(sb, "Name using character set %s contains a character that "
+		   "cannot be converted to unicode.", nls->charset);
+	befs_debug(sb, "<--- %s", __func__);
+	kfree(result);
+	return -EILSEQ;
+}
+
+/**
+ * befs_nls2utf - Convert NLS string to utf8 encodeing
+ * @sb: Superblock
+ * @in: Input string buffer in NLS format
+ * @in_len: Length of input string in bytes
+ * @out: The output string in UTF-8 format
+ * @out_len: Length of the output buffer
+ *
+ * Converts input string @in, which is in the format of the loaded NLS map,
+ * into a utf8 string.
+ *
+ * The destination string @out is allocated by this function and the caller is
+ * responsible for freeing it with kfree()
+ *
+ * On return, *@out_len is the length of @out in bytes.
+ *
+ * On success, the return value is the number of utf8 characters written to
+ * the output buffer @out.
+ *
+ * On Failure, a negative number coresponding to the error code is returned.
+ */
+
+static int
+befs_nls2utf(struct super_block *sb, const char *in,
+	     int in_len, char **out, int *out_len)
+{
+	struct nls_table *nls = BEFS_SB(sb)->nls;
+	int i, o;
+	wchar_t uni;
+	int unilen, utflen;
+	char *result;
+	/*
+	 * There are nls characters that will translate to 3-chars-wide UTF-8
+	 * characters, an additional byte is needed to save the final \0
+	 * in special cases
+	 */
+	int maxlen = (3 * in_len) + 1;
+
+	befs_debug(sb, "---> %s\n", __func__);
+
+	if (!nls) {
+		befs_error(sb, "%s called with no NLS table loaded.",
+			   __func__);
+		return -EINVAL;
+	}
+
+	*out = result = kmalloc(maxlen, GFP_NOFS);
+	if (!*out) {
+		*out_len = 0;
+		return -ENOMEM;
+	}
+
+	for (i = o = 0; i < in_len; i += unilen, o += utflen) {
+
+		/* convert from nls to unicode */
+		unilen = nls->char2uni(&in[i], in_len - i, &uni);
+		if (unilen < 0)
+			goto conv_err;
+
+		/* convert from unicode to UTF-8 */
+		utflen = utf32_to_utf8(uni, &result[o], 3);
+		if (utflen <= 0)
+			goto conv_err;
+	}
+
+	result[o] = '\0';
+	*out_len = o;
+
+	befs_debug(sb, "<--- %s", __func__);
+
+	return i;
+
+conv_err:
+	befs_error(sb, "Name using character set %s contains a character that "
+		   "cannot be converted to unicode.", nls->charset);
+	befs_debug(sb, "<--- %s", __func__);
+	kfree(result);
+	return -EILSEQ;
+}
+
+static struct inode *befs_nfs_get_inode(struct super_block *sb, uint64_t ino,
+					 uint32_t generation)
+{
+	/* No need to handle i_generation */
+	return befs_iget(sb, ino);
+}
+
+/*
+ * Map a NFS file handle to a corresponding dentry
+ */
+static struct dentry *befs_fh_to_dentry(struct super_block *sb,
+				struct fid *fid, int fh_len, int fh_type)
+{
+	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+				    befs_nfs_get_inode);
+}
+
+/*
+ * Find the parent for a file specified by NFS handle
+ */
+static struct dentry *befs_fh_to_parent(struct super_block *sb,
+				struct fid *fid, int fh_len, int fh_type)
+{
+	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+				    befs_nfs_get_inode);
+}
+
+static struct dentry *befs_get_parent(struct dentry *child)
+{
+	struct inode *parent;
+	struct befs_inode_info *befs_ino = BEFS_I(d_inode(child));
+
+	parent = befs_iget(child->d_sb,
+			   (unsigned long)befs_ino->i_parent.start);
+	return d_obtain_alias(parent);
+}
+
+enum {
+	Opt_uid, Opt_gid, Opt_charset, Opt_debug,
+};
+
+static const struct fs_parameter_spec befs_param_spec[] = {
+	fsparam_uid	("uid",		Opt_uid),
+	fsparam_gid	("gid",		Opt_gid),
+	fsparam_string	("iocharset",	Opt_charset),
+	fsparam_flag	("debug",	Opt_debug),
+	{}
+};
+
+static int
+befs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct befs_mount_options *opts = fc->fs_private;
+	int token;
+	struct fs_parse_result result;
+
+	/* befs ignores all options on remount */
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE)
+		return 0;
+
+	token = fs_parse(fc, befs_param_spec, param, &result);
+	if (token < 0)
+		return token;
+
+	switch (token) {
+	case Opt_uid:
+		opts->uid = result.uid;
+		opts->use_uid = 1;
+		break;
+	case Opt_gid:
+		opts->gid = result.gid;
+		opts->use_gid = 1;
+		break;
+	case Opt_charset:
+		kfree(opts->iocharset);
+		opts->iocharset = param->string;
+		param->string = NULL;
+		break;
+	case Opt_debug:
+		opts->debug = 1;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int befs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct befs_sb_info *befs_sb = BEFS_SB(root->d_sb);
+	struct befs_mount_options *opts = &befs_sb->mount_opts;
+
+	if (!uid_eq(opts->uid, GLOBAL_ROOT_UID))
+		seq_printf(m, ",uid=%u",
+			   from_kuid_munged(&init_user_ns, opts->uid));
+	if (!gid_eq(opts->gid, GLOBAL_ROOT_GID))
+		seq_printf(m, ",gid=%u",
+			   from_kgid_munged(&init_user_ns, opts->gid));
+	if (opts->iocharset)
+		seq_printf(m, ",charset=%s", opts->iocharset);
+	if (opts->debug)
+		seq_puts(m, ",debug");
+	return 0;
+}
+
+/* This function has the responsibiltiy of getting the
+ * filesystem ready for unmounting.
+ * Basically, we free everything that we allocated in
+ * befs_read_inode
+ */
+static void
+befs_put_super(struct super_block *sb)
+{
+	kfree(BEFS_SB(sb)->mount_opts.iocharset);
+	BEFS_SB(sb)->mount_opts.iocharset = NULL;
+	unload_nls(BEFS_SB(sb)->nls);
+	kfree(sb->s_fs_info);
+	sb->s_fs_info = NULL;
+}
+
+/*
+ * Copy the parsed options into the sbi mount_options member
+ */
+static void
+befs_set_options(struct befs_sb_info *sbi, struct befs_mount_options *opts)
+{
+	sbi->mount_opts.uid = opts->uid;
+	sbi->mount_opts.gid = opts->gid;
+	sbi->mount_opts.use_uid = opts->use_uid;
+	sbi->mount_opts.use_gid = opts->use_gid;
+	sbi->mount_opts.debug = opts->debug;
+	sbi->mount_opts.iocharset = opts->iocharset;
+	opts->iocharset = NULL;
+}
+
+/* Allocate private field of the superblock, fill it.
+ *
+ * Finish filling the public superblock fields
+ * Make the root directory
+ * Load a set of NLS translations if needed.
+ */
+static int
+befs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct buffer_head *bh;
+	struct befs_sb_info *befs_sb;
+	befs_super_block *disk_sb;
+	struct inode *root;
+	long ret = -EINVAL;
+	const unsigned long sb_block = 0;
+	const off_t x86_sb_off = 512;
+	int blocksize;
+	struct befs_mount_options *parsed_opts = fc->fs_private;
+	int silent = fc->sb_flags & SB_SILENT;
+
+	sb->s_fs_info = kzalloc_obj(*befs_sb);
+	if (sb->s_fs_info == NULL)
+		goto unacquire_none;
+
+	befs_sb = BEFS_SB(sb);
+
+	befs_set_options(befs_sb, parsed_opts);
+
+	befs_debug(sb, "---> %s", __func__);
+
+	if (!sb_rdonly(sb)) {
+		befs_warning(sb,
+			     "No write support. Marking filesystem read-only");
+		sb->s_flags |= SB_RDONLY;
+	}
+
+	/*
+	 * Set dummy blocksize to read super block.
+	 * Will be set to real fs blocksize later.
+	 *
+	 * Linux 2.4.10 and later refuse to read blocks smaller than
+	 * the logical block size for the device. But we also need to read at
+	 * least 1k to get the second 512 bytes of the volume.
+	 */
+	blocksize = sb_min_blocksize(sb, 1024);
+	if (!blocksize) {
+		if (!silent)
+			befs_error(sb, "unable to set blocksize");
+		goto unacquire_priv_sbp;
+	}
+
+	bh = sb_bread(sb, sb_block);
+	if (!bh) {
+		if (!silent)
+			befs_error(sb, "unable to read superblock");
+		goto unacquire_priv_sbp;
+	}
+
+	/* account for offset of super block on x86 */
+	disk_sb = (befs_super_block *) bh->b_data;
+	if ((disk_sb->magic1 == BEFS_SUPER_MAGIC1_LE) ||
+	    (disk_sb->magic1 == BEFS_SUPER_MAGIC1_BE)) {
+		befs_debug(sb, "Using PPC superblock location");
+	} else {
+		befs_debug(sb, "Using x86 superblock location");
+		disk_sb =
+		    (befs_super_block *) ((void *) bh->b_data + x86_sb_off);
+	}
+
+	if ((befs_load_sb(sb, disk_sb) != BEFS_OK) ||
+	    (befs_check_sb(sb) != BEFS_OK))
+		goto unacquire_bh;
+
+	befs_dump_super_block(sb, disk_sb);
+
+	brelse(bh);
+
+	if (befs_sb->num_blocks > ~((sector_t)0)) {
+		if (!silent)
+			befs_error(sb, "blocks count: %llu is larger than the host can use",
+					befs_sb->num_blocks);
+		goto unacquire_priv_sbp;
+	}
+
+	/*
+	 * set up enough so that it can read an inode
+	 * Fill in kernel superblock fields from private sb
+	 */
+	sb->s_magic = BEFS_SUPER_MAGIC;
+	/* Set real blocksize of fs */
+	if (!sb_set_blocksize(sb, (ulong) befs_sb->block_size))
+		goto unacquire_priv_sbp;
+	sb->s_op = &befs_sops;
+	sb->s_export_op = &befs_export_operations;
+	sb->s_time_min = 0;
+	sb->s_time_max = 0xffffffffffffll;
+	root = befs_iget(sb, iaddr2blockno(sb, &(befs_sb->root_dir)));
+	if (IS_ERR(root)) {
+		ret = PTR_ERR(root);
+		goto unacquire_priv_sbp;
+	}
+	sb->s_root = d_make_root(root);
+	if (!sb->s_root) {
+		if (!silent)
+			befs_error(sb, "get root inode failed");
+		goto unacquire_priv_sbp;
+	}
+
+	/* load nls library */
+	if (befs_sb->mount_opts.iocharset) {
+		befs_debug(sb, "Loading nls: %s",
+			   befs_sb->mount_opts.iocharset);
+		befs_sb->nls = load_nls(befs_sb->mount_opts.iocharset);
+		if (!befs_sb->nls) {
+			befs_warning(sb, "Cannot load nls %s"
+					" loading default nls",
+					befs_sb->mount_opts.iocharset);
+			befs_sb->nls = load_nls_default();
+		}
+	/* load default nls if none is specified  in mount options */
+	} else {
+		befs_debug(sb, "Loading default nls");
+		befs_sb->nls = load_nls_default();
+	}
+
+	return 0;
+
+unacquire_bh:
+	brelse(bh);
+
+unacquire_priv_sbp:
+	kfree(befs_sb->mount_opts.iocharset);
+	kfree(sb->s_fs_info);
+	sb->s_fs_info = NULL;
+
+unacquire_none:
+	return ret;
+}
+
+static int
+befs_reconfigure(struct fs_context *fc)
+{
+	sync_filesystem(fc->root->d_sb);
+	if (!(fc->sb_flags & SB_RDONLY))
+		return -EINVAL;
+	return 0;
+}
+
+static int
+befs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+
+	befs_debug(sb, "---> %s", __func__);
+
+	buf->f_type = BEFS_SUPER_MAGIC;
+	buf->f_bsize = sb->s_blocksize;
+	buf->f_blocks = BEFS_SB(sb)->num_blocks;
+	buf->f_bfree = BEFS_SB(sb)->num_blocks - BEFS_SB(sb)->used_blocks;
+	buf->f_bavail = buf->f_bfree;
+	buf->f_files = 0;	/* UNKNOWN */
+	buf->f_ffree = 0;	/* UNKNOWN */
+	buf->f_fsid = u64_to_fsid(id);
+	buf->f_namelen = BEFS_NAME_LEN;
+
+	befs_debug(sb, "<--- %s", __func__);
+
+	return 0;
+}
+
+static int befs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, befs_fill_super);
+}
+
+static const struct fs_context_operations befs_context_ops = {
+	.parse_param	= befs_parse_param,
+	.get_tree	= befs_get_tree,
+	.reconfigure	= befs_reconfigure,
+	.free		= befs_free_fc,
+};
+
+static int befs_init_fs_context(struct fs_context *fc)
+{
+	struct befs_mount_options *opts;
+
+	opts = kzalloc_obj(*opts);
+	if (!opts)
+		return -ENOMEM;
+
+	/* Initialize options */
+	opts->uid = GLOBAL_ROOT_UID;
+	opts->gid = GLOBAL_ROOT_GID;
+
+	fc->fs_private = opts;
+	fc->ops = &befs_context_ops;
+
+	return 0;
+}
+
+static void befs_free_fc(struct fs_context *fc)
+{
+	struct befs_mount_options *opts = fc->fs_private;
+
+	kfree(opts->iocharset);
+	kfree(fc->fs_private);
+}
+
+static struct file_system_type befs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "befs",
+	.kill_sb	= kill_block_super,
+	.fs_flags	= FS_REQUIRES_DEV,
+	.init_fs_context = befs_init_fs_context,
+	.parameters	= befs_param_spec,
+};
+MODULE_ALIAS_FS("befs");
+
+static int __init
+init_befs_fs(void)
+{
+	int err;
+
+	pr_info("version: %s\n", BEFS_VERSION);
+
+	err = befs_init_inodecache();
+	if (err)
+		goto unacquire_none;
+
+	err = register_filesystem(&befs_fs_type);
+	if (err)
+		goto unacquire_inodecache;
+
+	return 0;
+
+unacquire_inodecache:
+	befs_destroy_inodecache();
+
+unacquire_none:
+	return err;
+}
+
+static void __exit
+exit_befs_fs(void)
+{
+	befs_destroy_inodecache();
+
+	unregister_filesystem(&befs_fs_type);
+}
+
+/*
+ * Macros that typecheck the init and exit functions,
+ * ensures that they are called at init and cleanup,
+ * and eliminates warnings about unused functions.
+ */
+module_init(init_befs_fs)
+module_exit(exit_befs_fs)