[PATCH 21/25] fsinfo: pstore - add sb operation fsinfo() [ver #13]

From: David Howells
Date: Tue May 28 2019 - 11:17:29 EST


From: Ian Kent <raven@xxxxxxxxxx>

The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.

The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.

Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

fs/pstore/inode.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 4640debf8755..44f4ffc4436e 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -36,6 +36,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
+#include <linux/fsinfo.h>

#include "internal.h"

@@ -281,6 +282,33 @@ static int pstore_show_options(struct seq_file *m, struct dentry *root)
return 0;
}

+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int pstore_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_FLASH_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_CTIME);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_MTIME);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
+ fsinfo_note_paramf(params, "kmsg_bytes", "%lu", kmsg_bytes);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static int pstore_reconfigure(struct fs_context *fc)
{
sync_filesystem(fc->root->d_sb);
@@ -293,6 +321,9 @@ static const struct super_operations pstore_ops = {
.drop_inode = generic_delete_inode,
.evict_inode = pstore_evict_inode,
.show_options = pstore_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = pstore_fsinfo,
+#endif
};

static struct super_block *pstore_sb;