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Subject[PATCH 20/25] fsinfo: shmem - add tmpfs sb operation fsinfo() [ver #14]
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Date
From: Ian Kent <raven@themaw.net>

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.

Also add a simple FSINFO_ATTR_CAPABILITIES implementation.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
---

mm/shmem.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)

diff --git a/mm/shmem.c b/mm/shmem.c
index 38a77ee13db1..1a660ca7042f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -39,6 +39,7 @@
#include <linux/frontswap.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>

#include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */

@@ -1403,6 +1404,20 @@ static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
seq_printf(seq, ",mpol=%s", buffer);
}

+#ifdef CONFIG_FSINFO
+static void shmem_fsinfo_mpol(struct fsinfo_kparams *params, struct mempolicy *mpol)
+{
+ char buffer[64];
+
+ if (!mpol || mpol->mode == MPOL_DEFAULT)
+ return; /* show nothing */
+
+ mpol_to_str(buffer, sizeof(buffer), mpol);
+
+ fsinfo_note_paramf(params, "mpol", "%s", buffer);
+}
+#endif
+
static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
struct mempolicy *mpol = NULL;
@@ -1418,6 +1433,11 @@ static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
{
}
+#ifdef CONFIG_FSINFO
+static void shmem_fsinfo_mpol(struct fsinfo_kparams *params, struct mempolicy *mpol)
+{
+}
+#endif
static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
return NULL;
@@ -3478,7 +3498,9 @@ static int shmem_parse_param(struct fs_context *fc, struct fs_parameter *param)
struct shmem_fs_context *ctx = fc->fs_private;
struct fs_parse_result result;
unsigned long long size;
+#ifdef CONFIG_NUMA
struct mempolicy *mpol;
+#endif
char *rest;
int opt;

@@ -3623,6 +3645,53 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}

+#ifdef CONFIG_FSINFO
+static int shmem_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(path->dentry->d_sb);
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_unix_caps(caps);
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_MEMORY_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+#ifdef CONFIG_TMPFS_XATTR
+ fsinfo_set_cap(caps, FSINFO_CAP_XATTRS);
+#endif
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (sbinfo->max_blocks != shmem_default_max_blocks())
+ fsinfo_note_paramf(params, "size", "%luk",
+ sbinfo->max_blocks << (PAGE_SHIFT - 10));
+ if (sbinfo->max_inodes != shmem_default_max_inodes())
+ fsinfo_note_paramf(params, "nr_inodes",
+ "%lu", sbinfo->max_inodes);
+ if (sbinfo->mode != (0777 | S_ISVTX))
+ fsinfo_note_paramf(params, "mode",
+ "%03ho", sbinfo->mode);
+ if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, sbinfo->uid));
+ if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, sbinfo->gid));
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
+ /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
+ if (sbinfo->huge)
+ fsinfo_note_paramf(params, "huge", "%s",
+ shmem_format_huge(sbinfo->huge));
+#endif
+ shmem_fsinfo_mpol(params, sbinfo->mpol);
+ return params->usage;
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
#endif /* CONFIG_TMPFS */

static void shmem_put_super(struct super_block *sb)
@@ -3854,6 +3923,9 @@ static const struct super_operations shmem_ops = {
#ifdef CONFIG_TMPFS
.statfs = shmem_statfs,
.show_options = shmem_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = shmem_fsinfo,
+#endif
#endif
.evict_inode = shmem_evict_inode,
.drop_inode = generic_delete_inode,
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