Merge tag 'pstore-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore updates from Kees Cook:
 "This has a large internal refactoring along with several smaller
  fixes.

   - constify compression structures; Bhumika Goyal

   - restore powerpc dumping; Ankit Kumar

   - fix more bugs in the rarely exercises module unloading logic

   - reorganize filesystem locking to fix problems noticed by lockdep

   - refactor internal pstore APIs to make development and review
     easier:
      - improve error reporting
      - add kernel-doc structure and function comments
      - avoid insane argument passing by using a common record
        structure"

* tag 'pstore-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits)
  pstore: Solve lockdep warning by moving inode locks
  pstore: Fix flags to enable dumps on powerpc
  pstore: Remove unused vmalloc.h in pmsg
  pstore: simplify write_user_compat()
  pstore: Remove write_buf() callback
  pstore: Replace arguments for write_buf_user() API
  pstore: Replace arguments for write_buf() API
  pstore: Replace arguments for erase() API
  pstore: Do not duplicate record metadata
  pstore: Allocate records on heap instead of stack
  pstore: Pass record contents instead of copying
  pstore: Always allocate buffer for decompression
  pstore: Replace arguments for write() API
  pstore: Replace arguments for read() API
  pstore: Switch pstore_mkfile to pass record
  pstore: Move record decompression to function
  pstore: Extract common arguments into structure
  pstore: Add kernel-doc for struct pstore_info
  pstore: Improve register_pstore() error reporting
  pstore: Avoid race in module unloading
  ...

7 files changed, 350 insertions, 261 deletions

diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index 899d0ba0bd6c..06aab07b6bb7 100644
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -37,6 +37,12 @@ static void notrace pstore_ftrace_call(unsigned long ip,
 {
 	unsigned long flags;
 	struct pstore_ftrace_record rec = {};
+	struct pstore_record record = {
+		.type = PSTORE_TYPE_FTRACE,
+		.buf = (char *)&rec,
+		.size = sizeof(rec),
+		.psi = psinfo,
+	};
 
 	if (unlikely(oops_in_progress))
 		return;
@@ -47,8 +53,7 @@ static void notrace pstore_ftrace_call(unsigned long ip,
 	rec.parent_ip = parent_ip;
 	pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
 	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
-	psinfo->write_buf(PSTORE_TYPE_FTRACE, 0, NULL, 0, (void *)&rec,
-			  0, sizeof(rec), psinfo);
+	psinfo->write(&record);
 
 	local_irq_restore(flags);
 }
@@ -117,7 +122,7 @@ void pstore_register_ftrace(void)
 {
 	struct dentry *file;
 
-	if (!psinfo->write_buf)
+	if (!psinfo->write)
 		return;
 
 	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 57c0646479f5..792a4e5f9226 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -47,12 +47,8 @@ static LIST_HEAD(allpstore);
 
 struct pstore_private {
 	struct list_head list;
-	struct pstore_info *psi;
-	enum pstore_type_id type;
-	u64	id;
-	int	count;
-	ssize_t	size;
-	char	data[];
+	struct pstore_record *record;
+	size_t total_size;
 };
 
 struct pstore_ftrace_seq_data {
@@ -63,6 +59,17 @@ struct pstore_ftrace_seq_data {
 
 #define REC_SIZE sizeof(struct pstore_ftrace_record)
 
+static void free_pstore_private(struct pstore_private *private)
+{
+	if (!private)
+		return;
+	if (private->record) {
+		kfree(private->record->buf);
+		kfree(private->record);
+	}
+	kfree(private);
+}
+
 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 {
 	struct pstore_private *ps = s->private;
@@ -72,9 +79,9 @@ static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 	if (!data)
 		return NULL;
 
-	data->off = ps->size % REC_SIZE;
+	data->off = ps->total_size % REC_SIZE;
 	data->off += *pos * REC_SIZE;
-	if (data->off + REC_SIZE > ps->size) {
+	if (data->off + REC_SIZE > ps->total_size) {
 		kfree(data);
 		return NULL;
 	}
@@ -94,7 +101,7 @@ static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
 	struct pstore_ftrace_seq_data *data = v;
 
 	data->off += REC_SIZE;
-	if (data->off + REC_SIZE > ps->size)
+	if (data->off + REC_SIZE > ps->total_size)
 		return NULL;
 
 	(*pos)++;
@@ -105,7 +112,9 @@ static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
 {
 	struct pstore_private *ps = s->private;
 	struct pstore_ftrace_seq_data *data = v;
-	struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
+	struct pstore_ftrace_record *rec;
+
+	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
 
 	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
 		   pstore_ftrace_decode_cpu(rec),
@@ -125,7 +134,7 @@ static const struct seq_operations pstore_ftrace_seq_ops = {
 
 static int pstore_check_syslog_permissions(struct pstore_private *ps)
 {
-	switch (ps->type) {
+	switch (ps->record->type) {
 	case PSTORE_TYPE_DMESG:
 	case PSTORE_TYPE_CONSOLE:
 		return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
@@ -141,9 +150,10 @@ static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
 	struct seq_file *sf = file->private_data;
 	struct pstore_private *ps = sf->private;
 
-	if (ps->type == PSTORE_TYPE_FTRACE)
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
 		return seq_read(file, userbuf, count, ppos);
-	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
+	return simple_read_from_buffer(userbuf, count, ppos,
+				       ps->record->buf, ps->total_size);
 }
 
 static int pstore_file_open(struct inode *inode, struct file *file)
@@ -157,7 +167,7 @@ static int pstore_file_open(struct inode *inode, struct file *file)
 	if (err)
 		return err;
 
-	if (ps->type == PSTORE_TYPE_FTRACE)
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
 		sops = &pstore_ftrace_seq_ops;
 
 	err = seq_open(file, sops);
@@ -193,20 +203,19 @@ static const struct file_operations pstore_file_operations = {
 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct pstore_private *p = d_inode(dentry)->i_private;
+	struct pstore_record *record = p->record;
 	int err;
 
 	err = pstore_check_syslog_permissions(p);
 	if (err)
 		return err;
 
-	if (p->psi->erase) {
-		mutex_lock(&p->psi->read_mutex);
-		p->psi->erase(p->type, p->id, p->count,
-			      d_inode(dentry)->i_ctime, p->psi);
-		mutex_unlock(&p->psi->read_mutex);
-	} else {
+	if (!record->psi->erase)
 		return -EPERM;
-	}
+
+	mutex_lock(&record->psi->read_mutex);
+	record->psi->erase(record);
+	mutex_unlock(&record->psi->read_mutex);
 
 	return simple_unlink(dir, dentry);
 }
@@ -221,7 +230,7 @@ static void pstore_evict_inode(struct inode *inode)
 		spin_lock_irqsave(&allpstore_lock, flags);
 		list_del(&p->list);
 		spin_unlock_irqrestore(&allpstore_lock, flags);
-		kfree(p);
+		free_pstore_private(p);
 	}
 }
 
@@ -302,23 +311,23 @@ bool pstore_is_mounted(void)
  * Load it up with "size" bytes of data from "buf".
  * Set the mtime & ctime to the date that this record was originally stored.
  */
-int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
-		  char *data, bool compressed, size_t size,
-		  struct timespec time, struct pstore_info *psi)
+int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 {
-	struct dentry		*root = pstore_sb->s_root;
 	struct dentry		*dentry;
 	struct inode		*inode;
 	int			rc = 0;
 	char			name[PSTORE_NAMELEN];
 	struct pstore_private	*private, *pos;
 	unsigned long		flags;
+	size_t			size = record->size + record->ecc_notice_size;
+
+	WARN_ON(!inode_is_locked(d_inode(root)));
 
 	spin_lock_irqsave(&allpstore_lock, flags);
 	list_for_each_entry(pos, &allpstore, list) {
-		if (pos->type == type &&
-		    pos->id == id &&
-		    pos->psi == psi) {
+		if (pos->record->type == record->type &&
+		    pos->record->id == record->id &&
+		    pos->record->psi == record->psi) {
 			rc = -EEXIST;
 			break;
 		}
@@ -328,72 +337,74 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
 		return rc;
 
 	rc = -ENOMEM;
-	inode = pstore_get_inode(pstore_sb);
+	inode = pstore_get_inode(root->d_sb);
 	if (!inode)
 		goto fail;
 	inode->i_mode = S_IFREG | 0444;
 	inode->i_fop = &pstore_file_operations;
-	private = kmalloc(sizeof *private + size, GFP_KERNEL);
+	private = kzalloc(sizeof(*private), GFP_KERNEL);
 	if (!private)
 		goto fail_alloc;
-	private->type = type;
-	private->id = id;
-	private->count = count;
-	private->psi = psi;
+	private->record = record;
 
-	switch (type) {
+	switch (record->type) {
 	case PSTORE_TYPE_DMESG:
 		scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
-			  psname, id, compressed ? ".enc.z" : "");
+			  record->psi->name, record->id,
+			  record->compressed ? ".enc.z" : "");
 		break;
 	case PSTORE_TYPE_CONSOLE:
-		scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "console-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_FTRACE:
-		scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "ftrace-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_MCE:
-		scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "mce-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_PPC_RTAS:
-		scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "rtas-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_PPC_OF:
 		scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
-			  psname, id);
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_PPC_COMMON:
 		scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
-			  psname, id);
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_PMSG:
-		scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "pmsg-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_PPC_OPAL:
-		sprintf(name, "powerpc-opal-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "powerpc-opal-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	case PSTORE_TYPE_UNKNOWN:
-		scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
+		scnprintf(name, sizeof(name), "unknown-%s-%lld",
+			  record->psi->name, record->id);
 		break;
 	default:
 		scnprintf(name, sizeof(name), "type%d-%s-%lld",
-			  type, psname, id);
+			  record->type, record->psi->name, record->id);
 		break;
 	}
 
-	inode_lock(d_inode(root));
-
 	dentry = d_alloc_name(root, name);
 	if (!dentry)
-		goto fail_lockedalloc;
+		goto fail_private;
 
-	memcpy(private->data, data, size);
-	inode->i_size = private->size = size;
+	inode->i_size = private->total_size = size;
 
 	inode->i_private = private;
 
-	if (time.tv_sec)
-		inode->i_mtime = inode->i_ctime = time;
+	if (record->time.tv_sec)
+		inode->i_mtime = inode->i_ctime = record->time;
 
 	d_add(dentry, inode);
 
@@ -401,13 +412,10 @@ int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
 	list_add(&private->list, &allpstore);
 	spin_unlock_irqrestore(&allpstore_lock, flags);
 
-	inode_unlock(d_inode(root));
-
 	return 0;
 
-fail_lockedalloc:
-	inode_unlock(d_inode(root));
-	kfree(private);
+fail_private:
+	free_pstore_private(private);
 fail_alloc:
 	iput(inode);
 
@@ -415,6 +423,27 @@ fail:
 	return rc;
 }
 
+/*
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_records(int quiet)
+{
+	struct pstore_info *psi = psinfo;
+	struct dentry *root;
+
+	if (!psi || !pstore_sb)
+		return;
+
+	root = pstore_sb->s_root;
+
+	inode_lock(d_inode(root));
+	pstore_get_backend_records(psi, root, quiet);
+	inode_unlock(d_inode(root));
+}
+
 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *inode;
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index da416e6591c9..c416e653dc4f 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -25,10 +25,10 @@ extern struct pstore_info *psinfo;
 
 extern void	pstore_set_kmsg_bytes(int);
 extern void	pstore_get_records(int);
-extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
-			      int count, char *data, bool compressed,
-			      size_t size, struct timespec time,
-			      struct pstore_info *psi);
+extern void	pstore_get_backend_records(struct pstore_info *psi,
+					   struct dentry *root, int quiet);
+extern int	pstore_mkfile(struct dentry *root,
+			      struct pstore_record *record);
 extern bool	pstore_is_mounted(void);
 
 #endif
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index efab7b64925b..d468eec9b8a6 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -267,7 +267,7 @@ static void free_zlib(void)
 	big_oops_buf_sz = 0;
 }
 
-static struct pstore_zbackend backend_zlib = {
+static const struct pstore_zbackend backend_zlib = {
 	.compress	= compress_zlib,
 	.decompress	= decompress_zlib,
 	.allocate	= allocate_zlib,
@@ -328,7 +328,7 @@ static void free_lzo(void)
 	big_oops_buf_sz = 0;
 }
 
-static struct pstore_zbackend backend_lzo = {
+static const struct pstore_zbackend backend_lzo = {
 	.compress	= compress_lzo,
 	.decompress	= decompress_lzo,
 	.allocate	= allocate_lzo,
@@ -393,7 +393,7 @@ static void free_lz4(void)
 	big_oops_buf_sz = 0;
 }
 
-static struct pstore_zbackend backend_lz4 = {
+static const struct pstore_zbackend backend_lz4 = {
 	.compress	= compress_lz4,
 	.decompress	= decompress_lz4,
 	.allocate	= allocate_lz4,
@@ -402,7 +402,7 @@ static struct pstore_zbackend backend_lz4 = {
 };
 #endif
 
-static struct pstore_zbackend *zbackend =
+static const struct pstore_zbackend *zbackend =
 #if defined(CONFIG_PSTORE_ZLIB_COMPRESS)
 	&backend_zlib;
 #elif defined(CONFIG_PSTORE_LZO_COMPRESS)
@@ -484,7 +484,6 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 {
 	unsigned long	total = 0;
 	const char	*why;
-	u64		id;
 	unsigned int	part = 1;
 	unsigned long	flags = 0;
 	int		is_locked;
@@ -506,48 +505,59 @@ static void pstore_dump(struct kmsg_dumper *dumper,
 	oopscount++;
 	while (total < kmsg_bytes) {
 		char *dst;
-		unsigned long size;
-		int hsize;
+		size_t dst_size;
+		int header_size;
 		int zipped_len = -1;
-		size_t len;
-		bool compressed = false;
-		size_t total_len;
+		size_t dump_size;
+		struct pstore_record record = {
+			.type = PSTORE_TYPE_DMESG,
+			.count = oopscount,
+			.reason = reason,
+			.part = part,
+			.compressed = false,
+			.buf = psinfo->buf,
+			.psi = psinfo,
+		};
 
 		if (big_oops_buf && is_locked) {
 			dst = big_oops_buf;
-			size = big_oops_buf_sz;
+			dst_size = big_oops_buf_sz;
 		} else {
 			dst = psinfo->buf;
-			size = psinfo->bufsize;
+			dst_size = psinfo->bufsize;
 		}
 
-		hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount, part);
-		size -= hsize;
+		/* Write dump header. */
+		header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
+				 oopscount, part);
+		dst_size -= header_size;
 
-		if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
-					  size, &len))
+		/* Write dump contents. */
+		if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
+					  dst_size, &dump_size))
 			break;
 
 		if (big_oops_buf && is_locked) {
 			zipped_len = pstore_compress(dst, psinfo->buf,
-						hsize + len, psinfo->bufsize);
+						header_size + dump_size,
+						psinfo->bufsize);
 
 			if (zipped_len > 0) {
-				compressed = true;
-				total_len = zipped_len;
+				record.compressed = true;
+				record.size = zipped_len;
 			} else {
-				total_len = copy_kmsg_to_buffer(hsize, len);
+				record.size = copy_kmsg_to_buffer(header_size,
+								  dump_size);
 			}
 		} else {
-			total_len = hsize + len;
+			record.size = header_size + dump_size;
 		}
 
-		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
-				    oopscount, compressed, total_len, psinfo);
+		ret = psinfo->write(&record);
 		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
 			pstore_new_entry = 1;
 
-		total += total_len;
+		total += record.size;
 		part++;
 	}
 	if (is_locked)
@@ -577,8 +587,11 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
 	const char *e = s + c;
 
 	while (s < e) {
+		struct pstore_record record = {
+			.type = PSTORE_TYPE_CONSOLE,
+			.psi = psinfo,
+		};
 		unsigned long flags;
-		u64 id;
 
 		if (c > psinfo->bufsize)
 			c = psinfo->bufsize;
@@ -589,8 +602,9 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
 		} else {
 			spin_lock_irqsave(&psinfo->buf_lock, flags);
 		}
-		psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
-				  s, 0, c, psinfo);
+		record.buf = (char *)s;
+		record.size = c;
+		psinfo->write(&record);
 		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 		s += c;
 		c = e - s;
@@ -618,48 +632,30 @@ static void pstore_register_console(void) {}
 static void pstore_unregister_console(void) {}
 #endif
 
-static int pstore_write_compat(enum pstore_type_id type,
-			       enum kmsg_dump_reason reason,
-			       u64 *id, unsigned int part, int count,
-			       bool compressed, size_t size,
-			       struct pstore_info *psi)
-{
-	return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
-			     size, psi);
-}
-
-static int pstore_write_buf_user_compat(enum pstore_type_id type,
-			       enum kmsg_dump_reason reason,
-			       u64 *id, unsigned int part,
-			       const char __user *buf,
-			       bool compressed, size_t size,
-			       struct pstore_info *psi)
-{
-	unsigned long flags = 0;
-	size_t i, bufsize = size;
-	long ret = 0;
-
-	if (unlikely(!access_ok(VERIFY_READ, buf, size)))
-		return -EFAULT;
-	if (bufsize > psinfo->bufsize)
-		bufsize = psinfo->bufsize;
-	spin_lock_irqsave(&psinfo->buf_lock, flags);
-	for (i = 0; i < size; ) {
-		size_t c = min(size - i, bufsize);
-
-		ret = __copy_from_user(psinfo->buf, buf + i, c);
-		if (unlikely(ret != 0)) {
-			ret = -EFAULT;
-			break;
-		}
-		ret = psi->write_buf(type, reason, id, part, psinfo->buf,
-				     compressed, c, psi);
-		if (unlikely(ret < 0))
-			break;
-		i += c;
+static int pstore_write_user_compat(struct pstore_record *record,
+				    const char __user *buf)
+{
+	int ret = 0;
+
+	if (record->buf)
+		return -EINVAL;
+
+	record->buf = kmalloc(record->size, GFP_KERNEL);
+	if (!record->buf)
+		return -ENOMEM;
+
+	if (unlikely(copy_from_user(record->buf, buf, record->size))) {
+		ret = -EFAULT;
+		goto out;
 	}
-	spin_unlock_irqrestore(&psinfo->buf_lock, flags);
-	return unlikely(ret < 0) ? ret : size;
+
+	ret = record->psi->write(record);
+
+out:
+	kfree(record->buf);
+	record->buf = NULL;
+
+	return unlikely(ret < 0) ? ret : record->size;
 }
 
 /*
@@ -673,19 +669,35 @@ int pstore_register(struct pstore_info *psi)
 {
 	struct module *owner = psi->owner;
 
-	if (backend && strcmp(backend, psi->name))
+	if (backend && strcmp(backend, psi->name)) {
+		pr_warn("ignoring unexpected backend '%s'\n", psi->name);
 		return -EPERM;
+	}
+
+	/* Sanity check flags. */
+	if (!psi->flags) {
+		pr_warn("backend '%s' must support at least one frontend\n",
+			psi->name);
+		return -EINVAL;
+	}
+
+	/* Check for required functions. */
+	if (!psi->read || !psi->write) {
+		pr_warn("backend '%s' must implement read() and write()\n",
+			psi->name);
+		return -EINVAL;
+	}
 
 	spin_lock(&pstore_lock);
 	if (psinfo) {
+		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
+			psinfo->name, psi->name);
 		spin_unlock(&pstore_lock);
 		return -EBUSY;
 	}
 
-	if (!psi->write)
-		psi->write = pstore_write_compat;
-	if (!psi->write_buf_user)
-		psi->write_buf_user = pstore_write_buf_user_compat;
+	if (!psi->write_user)
+		psi->write_user = pstore_write_user_compat;
 	psinfo = psi;
 	mutex_init(&psinfo->read_mutex);
 	spin_unlock(&pstore_lock);
@@ -709,6 +721,7 @@ int pstore_register(struct pstore_info *psi)
 	if (psi->flags & PSTORE_FLAGS_PMSG)
 		pstore_register_pmsg();
 
+	/* Start watching for new records, if desired. */
 	if (pstore_update_ms >= 0) {
 		pstore_timer.expires = jiffies +
 			msecs_to_jiffies(pstore_update_ms);
@@ -721,16 +734,21 @@ int pstore_register(struct pstore_info *psi)
 	 */
 	backend = psi->name;
 
-	module_put(owner);
-
 	pr_info("Registered %s as persistent store backend\n", psi->name);
 
+	module_put(owner);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pstore_register);
 
 void pstore_unregister(struct pstore_info *psi)
 {
+	/* Stop timer and make sure all work has finished. */
+	pstore_update_ms = -1;
+	del_timer_sync(&pstore_timer);
+	flush_work(&pstore_work);
+
 	if (psi->flags & PSTORE_FLAGS_PMSG)
 		pstore_unregister_pmsg();
 	if (psi->flags & PSTORE_FLAGS_FTRACE)
@@ -747,66 +765,99 @@ void pstore_unregister(struct pstore_info *psi)
 }
 EXPORT_SYMBOL_GPL(pstore_unregister);
 
+static void decompress_record(struct pstore_record *record)
+{
+	int unzipped_len;
+	char *decompressed;
+
+	/* Only PSTORE_TYPE_DMESG support compression. */
+	if (!record->compressed || record->type != PSTORE_TYPE_DMESG) {
+		pr_warn("ignored compressed record type %d\n", record->type);
+		return;
+	}
+
+	/* No compression method has created the common buffer. */
+	if (!big_oops_buf) {
+		pr_warn("no decompression buffer allocated\n");
+		return;
+	}
+
+	unzipped_len = pstore_decompress(record->buf, big_oops_buf,
+					 record->size, big_oops_buf_sz);
+	if (unzipped_len <= 0) {
+		pr_err("decompression failed: %d\n", unzipped_len);
+		return;
+	}
+
+	/* Build new buffer for decompressed contents. */
+	decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
+			       GFP_KERNEL);
+	if (!decompressed) {
+		pr_err("decompression ran out of memory\n");
+		return;
+	}
+	memcpy(decompressed, big_oops_buf, unzipped_len);
+
+	/* Append ECC notice to decompressed buffer. */
+	memcpy(decompressed + unzipped_len, record->buf + record->size,
+	       record->ecc_notice_size);
+
+	/* Swap out compresed contents with decompressed contents. */
+	kfree(record->buf);
+	record->buf = decompressed;
+	record->size = unzipped_len;
+	record->compressed = false;
+}
+
 /*
- * Read all the records from the persistent store. Create
+ * Read all the records from one persistent store backend. Create
  * files in our filesystem.  Don't warn about -EEXIST errors
  * when we are re-scanning the backing store looking to add new
  * error records.
  */
-void pstore_get_records(int quiet)
-{
-	struct pstore_info *psi = psinfo;
-	char			*buf = NULL;
-	ssize_t			size;
-	u64			id;
-	int			count;
-	enum pstore_type_id	type;
-	struct timespec		time;
-	int			failed = 0, rc;
-	bool			compressed;
-	int			unzipped_len = -1;
-	ssize_t			ecc_notice_size = 0;
-
-	if (!psi)
+void pstore_get_backend_records(struct pstore_info *psi,
+				struct dentry *root, int quiet)
+{
+	int failed = 0;
+
+	if (!psi || !root)
 		return;
 
 	mutex_lock(&psi->read_mutex);
 	if (psi->open && psi->open(psi))
 		goto out;
 
-	while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
-				 &ecc_notice_size, psi)) > 0) {
-		if (compressed && (type == PSTORE_TYPE_DMESG)) {
-			if (big_oops_buf)
-				unzipped_len = pstore_decompress(buf,
-							big_oops_buf, size,
-							big_oops_buf_sz);
-
-			if (unzipped_len > 0) {
-				if (ecc_notice_size)
-					memcpy(big_oops_buf + unzipped_len,
-					       buf + size, ecc_notice_size);
-				kfree(buf);
-				buf = big_oops_buf;
-				size = unzipped_len;
-				compressed = false;
-			} else {
-				pr_err("decompression failed;returned %d\n",
-				       unzipped_len);
-				compressed = true;
-			}
+	/*
+	 * Backend callback read() allocates record.buf. decompress_record()
+	 * may reallocate record.buf. On success, pstore_mkfile() will keep
+	 * the record.buf, so free it only on failure.
+	 */
+	for (;;) {
+		struct pstore_record *record;
+		int rc;
+
+		record = kzalloc(sizeof(*record), GFP_KERNEL);
+		if (!record) {
+			pr_err("out of memory creating record\n");
+			break;
+		}
+		record->psi = psi;
+
+		record->size = psi->read(record);
+
+		/* No more records left in backend? */
+		if (record->size <= 0)
+			break;
+
+		decompress_record(record);
+		rc = pstore_mkfile(root, record);
+		if (rc) {
+			/* pstore_mkfile() did not take record, so free it. */
+			kfree(record->buf);
+			kfree(record);
+			if (rc != -EEXIST || !quiet)
+				failed++;
 		}
-		rc = pstore_mkfile(type, psi->name, id, count, buf,
-				   compressed, size + ecc_notice_size,
-				   time, psi);
-		if (unzipped_len < 0) {
-			/* Free buffer other than big oops */
-			kfree(buf);
-			buf = NULL;
-		} else
-			unzipped_len = -1;
-		if (rc && (rc != -EEXIST || !quiet))
-			failed++;
 	}
 	if (psi->close)
 		psi->close(psi);
@@ -830,7 +881,9 @@ static void pstore_timefunc(unsigned long dummy)
 		schedule_work(&pstore_work);
 	}
 
-	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
+	if (pstore_update_ms >= 0)
+		mod_timer(&pstore_timer,
+			  jiffies + msecs_to_jiffies(pstore_update_ms));
 }
 
 module_param(backend, charp, 0444);
diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
index 78f6176c020f..209755e0d7c8 100644
--- a/fs/pstore/pmsg.c
+++ b/fs/pstore/pmsg.c
@@ -15,7 +15,6 @@
 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
-#include <linux/vmalloc.h>
 #include "internal.h"
 
 static DEFINE_MUTEX(pmsg_lock);
@@ -23,19 +22,22 @@ static DEFINE_MUTEX(pmsg_lock);
 static ssize_t write_pmsg(struct file *file, const char __user *buf,
 			  size_t count, loff_t *ppos)
 {
-	u64 id;
+	struct pstore_record record = {
+		.type = PSTORE_TYPE_PMSG,
+		.size = count,
+		.psi = psinfo,
+	};
 	int ret;
 
 	if (!count)
 		return 0;
 
-	/* check outside lock, page in any data. write_buf_user also checks */
+	/* check outside lock, page in any data. write_user also checks */
 	if (!access_ok(VERIFY_READ, buf, count))
 		return -EFAULT;
 
 	mutex_lock(&pmsg_lock);
-	ret = psinfo->write_buf_user(PSTORE_TYPE_PMSG, 0, &id, 0, buf, 0, count,
-				     psinfo);
+	ret = psinfo->write_user(&record, buf);
 	mutex_unlock(&pmsg_lock);
 	return ret ? ret : count;
 }
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 11f918d34b1e..5523df7f17ef 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -235,35 +235,34 @@ static ssize_t ftrace_log_combine(struct persistent_ram_zone *dest,
 	return 0;
 }
 
-static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
-				   int *count, struct timespec *time,
-				   char **buf, bool *compressed,
-				   ssize_t *ecc_notice_size,
-				   struct pstore_info *psi)
+static ssize_t ramoops_pstore_read(struct pstore_record *record)
 {
 	ssize_t size = 0;
-	struct ramoops_context *cxt = psi->data;
+	struct ramoops_context *cxt = record->psi->data;
 	struct persistent_ram_zone *prz = NULL;
 	int header_length = 0;
 	bool free_prz = false;
 
-	/* Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
+	/*
+	 * Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
 	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
 	 * valid time stamps, so it is initialized to zero.
 	 */
-	time->tv_sec = 0;
-	time->tv_nsec = 0;
-	*compressed = false;
+	record->time.tv_sec = 0;
+	record->time.tv_nsec = 0;
+	record->compressed = false;
 
 	/* Find the next valid persistent_ram_zone for DMESG */
 	while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {
 		prz = ramoops_get_next_prz(cxt->dprzs, &cxt->dump_read_cnt,
-					   cxt->max_dump_cnt, id, type,
+					   cxt->max_dump_cnt, &record->id,
+					   &record->type,
 					   PSTORE_TYPE_DMESG, 1);
 		if (!prz_ok(prz))
 			continue;
 		header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
-						      time, compressed);
+						      &record->time,
+						      &record->compressed);
 		/* Clear and skip this DMESG record if it has no valid header */
 		if (!header_length) {
 			persistent_ram_free_old(prz);
@@ -274,18 +273,20 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 
 	if (!prz_ok(prz))
 		prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt,
-					   1, id, type, PSTORE_TYPE_CONSOLE, 0);
+					   1, &record->id, &record->type,
+					   PSTORE_TYPE_CONSOLE, 0);
 
 	if (!prz_ok(prz))
 		prz = ramoops_get_next_prz(&cxt->mprz, &cxt->pmsg_read_cnt,
-					   1, id, type, PSTORE_TYPE_PMSG, 0);
+					   1, &record->id, &record->type,
+					   PSTORE_TYPE_PMSG, 0);
 
 	/* ftrace is last since it may want to dynamically allocate memory. */
 	if (!prz_ok(prz)) {
 		if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)) {
 			prz = ramoops_get_next_prz(cxt->fprzs,
-					&cxt->ftrace_read_cnt, 1, id, type,
-					PSTORE_TYPE_FTRACE, 0);
+					&cxt->ftrace_read_cnt, 1, &record->id,
+					&record->type, PSTORE_TYPE_FTRACE, 0);
 		} else {
 			/*
 			 * Build a new dummy record which combines all the
@@ -302,8 +303,10 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
 				prz_next = ramoops_get_next_prz(cxt->fprzs,
 						&cxt->ftrace_read_cnt,
-						cxt->max_ftrace_cnt, id,
-						type, PSTORE_TYPE_FTRACE, 0);
+						cxt->max_ftrace_cnt,
+						&record->id,
+						&record->type,
+						PSTORE_TYPE_FTRACE, 0);
 
 				if (!prz_ok(prz_next))
 					continue;
@@ -316,7 +319,7 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 				if (size)
 					goto out;
 			}
-			*id = 0;
+			record->id = 0;
 			prz = tmp_prz;
 		}
 	}
@@ -329,17 +332,19 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type,
 	size = persistent_ram_old_size(prz) - header_length;
 
 	/* ECC correction notice */
-	*ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
+	record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
 
-	*buf = kmalloc(size + *ecc_notice_size + 1, GFP_KERNEL);
-	if (*buf == NULL) {
+	record->buf = kmalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
+	if (record->buf == NULL) {
 		size = -ENOMEM;
 		goto out;
 	}
 
-	memcpy(*buf, (char *)persistent_ram_old(prz) + header_length, size);
+	memcpy(record->buf, (char *)persistent_ram_old(prz) + header_length,
+	       size);
 
-	persistent_ram_ecc_string(prz, *buf + size, *ecc_notice_size + 1);
+	persistent_ram_ecc_string(prz, record->buf + size,
+				  record->ecc_notice_size + 1);
 
 out:
 	if (free_prz) {
@@ -373,23 +378,18 @@ static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
 	return len;
 }
 
-static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
-					    enum kmsg_dump_reason reason,
-					    u64 *id, unsigned int part,
-					    const char *buf,
-					    bool compressed, size_t size,
-					    struct pstore_info *psi)
+static int notrace ramoops_pstore_write(struct pstore_record *record)
 {
-	struct ramoops_context *cxt = psi->data;
+	struct ramoops_context *cxt = record->psi->data;
 	struct persistent_ram_zone *prz;
-	size_t hlen;
+	size_t size, hlen;
 
-	if (type == PSTORE_TYPE_CONSOLE) {
+	if (record->type == PSTORE_TYPE_CONSOLE) {
 		if (!cxt->cprz)
 			return -ENOMEM;
-		persistent_ram_write(cxt->cprz, buf, size);
+		persistent_ram_write(cxt->cprz, record->buf, record->size);
 		return 0;
-	} else if (type == PSTORE_TYPE_FTRACE) {
+	} else if (record->type == PSTORE_TYPE_FTRACE) {
 		int zonenum;
 
 		if (!cxt->fprzs)
@@ -402,33 +402,36 @@ static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
 		else
 			zonenum = 0;
 
-		persistent_ram_write(cxt->fprzs[zonenum], buf, size);
+		persistent_ram_write(cxt->fprzs[zonenum], record->buf,
+				     record->size);
 		return 0;
-	} else if (type == PSTORE_TYPE_PMSG) {
+	} else if (record->type == PSTORE_TYPE_PMSG) {
 		pr_warn_ratelimited("PMSG shouldn't call %s\n", __func__);
 		return -EINVAL;
 	}
 
-	if (type != PSTORE_TYPE_DMESG)
+	if (record->type != PSTORE_TYPE_DMESG)
 		return -EINVAL;
 
-	/* Out of the various dmesg dump types, ramoops is currently designed
+	/*
+	 * Out of the various dmesg dump types, ramoops is currently designed
 	 * to only store crash logs, rather than storing general kernel logs.
 	 */
-	if (reason != KMSG_DUMP_OOPS &&
-	    reason != KMSG_DUMP_PANIC)
+	if (record->reason != KMSG_DUMP_OOPS &&
+	    record->reason != KMSG_DUMP_PANIC)
 		return -EINVAL;
 
 	/* Skip Oopes when configured to do so. */
-	if (reason == KMSG_DUMP_OOPS && !cxt->dump_oops)
+	if (record->reason == KMSG_DUMP_OOPS && !cxt->dump_oops)
 		return -EINVAL;
 
-	/* Explicitly only take the first part of any new crash.
+	/*
+	 * Explicitly only take the first part of any new crash.
 	 * If our buffer is larger than kmsg_bytes, this can never happen,
 	 * and if our buffer is smaller than kmsg_bytes, we don't want the
 	 * report split across multiple records.
 	 */
-	if (part != 1)
+	if (record->part != 1)
 		return -ENOSPC;
 
 	if (!cxt->dprzs)
@@ -436,53 +439,50 @@ static int notrace ramoops_pstore_write_buf(enum pstore_type_id type,
 
 	prz = cxt->dprzs[cxt->dump_write_cnt];
 
-	hlen = ramoops_write_kmsg_hdr(prz, compressed);
+	/* Build header and append record contents. */
+	hlen = ramoops_write_kmsg_hdr(prz, record->compressed);
+	size = record->size;
 	if (size + hlen > prz->buffer_size)
 		size = prz->buffer_size - hlen;
-	persistent_ram_write(prz, buf, size);
+	persistent_ram_write(prz, record->buf, size);
 
 	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;
 
 	return 0;
 }
 
-static int notrace ramoops_pstore_write_buf_user(enum pstore_type_id type,
-						 enum kmsg_dump_reason reason,
-						 u64 *id, unsigned int part,
-						 const char __user *buf,
-						 bool compressed, size_t size,
-						 struct pstore_info *psi)
+static int notrace ramoops_pstore_write_user(struct pstore_record *record,
+					     const char __user *buf)
 {
-	if (type == PSTORE_TYPE_PMSG) {
-		struct ramoops_context *cxt = psi->data;
+	if (record->type == PSTORE_TYPE_PMSG) {
+		struct ramoops_context *cxt = record->psi->data;
 
 		if (!cxt->mprz)
 			return -ENOMEM;
-		return persistent_ram_write_user(cxt->mprz, buf, size);
+		return persistent_ram_write_user(cxt->mprz, buf, record->size);
 	}
 
 	return -EINVAL;
 }
 
-static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, int count,
-				struct timespec time, struct pstore_info *psi)
+static int ramoops_pstore_erase(struct pstore_record *record)
 {
-	struct ramoops_context *cxt = psi->data;
+	struct ramoops_context *cxt = record->psi->data;
 	struct persistent_ram_zone *prz;
 
-	switch (type) {
+	switch (record->type) {
 	case PSTORE_TYPE_DMESG:
-		if (id >= cxt->max_dump_cnt)
+		if (record->id >= cxt->max_dump_cnt)
 			return -EINVAL;
-		prz = cxt->dprzs[id];
+		prz = cxt->dprzs[record->id];
 		break;
 	case PSTORE_TYPE_CONSOLE:
 		prz = cxt->cprz;
 		break;
 	case PSTORE_TYPE_FTRACE:
-		if (id >= cxt->max_ftrace_cnt)
+		if (record->id >= cxt->max_ftrace_cnt)
 			return -EINVAL;
-		prz = cxt->fprzs[id];
+		prz = cxt->fprzs[record->id];
 		break;
 	case PSTORE_TYPE_PMSG:
 		prz = cxt->mprz;
@@ -503,8 +503,8 @@ static struct ramoops_context oops_cxt = {
 		.name	= "ramoops",
 		.open	= ramoops_pstore_open,
 		.read	= ramoops_pstore_read,
-		.write_buf	= ramoops_pstore_write_buf,
-		.write_buf_user	= ramoops_pstore_write_buf_user,
+		.write	= ramoops_pstore_write,
+		.write_user	= ramoops_pstore_write_user,
 		.erase	= ramoops_pstore_erase,
 	},
 };
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index bc927e30bdcc..e11672aa4575 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -532,7 +532,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 	}
 
 	/* Initialize general buffer state. */
-	prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock);
+	raw_spin_lock_init(&prz->buffer_lock);
 	prz->flags = flags;
 
 	ret = persistent_ram_buffer_map(start, size, prz, memtype);