Return Ext4 filesystem information through the filesystem info retrieval
system call. This includes the following:
(1) information about the capacity and resolution of the inode timestamps;
(2) the volume label as the volume name, setting FSINFO_VOLUME_NAME;
(3) the remote FSID as the volume ID, setting FSINFO_VOLUME_ID;
(4) the statfs information;
(5) a list of supported IOC flags.
Example output:
[root@andromeda ~]# ./test-fsinfo /var/cache/fscache/
fsinfo(/var/cache/fscache/) = 0
mask : 9f
dev : 08:06
fs : type=ef53 name=ext4
ioc : 4bdfff
nameln: 255
flags : 1020
times : range=ffffffff80000000-37fffffff
atime : gran=1e-09s
btime : gran=1e-09s
ctime : gran=1e-09s
mtime : gran=1e-09s
blocks: n=1123529 fr=208887 av=146054
files : n=293760 fr=225334 av=225334
bsize : 4096
frsize: 4096
fsid : 48bc815f32464608
volume: 'fred'
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/ext4/super.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a63c7b0a10cf..fbd1cad4ff3b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -73,6 +73,8 @@ static void ext4_clear_journal_err(struct super_block *sb,
static int ext4_sync_fs(struct super_block *sb, int wait);
static int ext4_remount(struct super_block *sb, int *flags, char *data);
static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf);
+static int ext4_get_fsinfo(struct dentry *dentry, struct fsinfo *f,
+ unsigned flags);
static int ext4_unfreeze(struct super_block *sb);
static int ext4_freeze(struct super_block *sb);
static struct dentry *ext4_mount(struct file_system_type *fs_type, int flags,
@@ -1122,6 +1124,7 @@ static const struct super_operations ext4_sops = {
.freeze_fs = ext4_freeze,
.unfreeze_fs = ext4_unfreeze,
.statfs = ext4_statfs,
+ .get_fsinfo = ext4_get_fsinfo,
.remount_fs = ext4_remount,
.show_options = ext4_show_options,
#ifdef CONFIG_QUOTA
@@ -3524,6 +3527,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
if (sb->s_magic != EXT4_SUPER_MAGIC)
goto cantfind_ext4;
sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written);
+ memcpy(sb->s_uuid, es->s_uuid, sizeof(sb->s_uuid));
/* Warn if metadata_csum and gdt_csum are both set. */
if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
@@ -5179,6 +5183,41 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
return 0;
}
+/*
+ * Read filesystem information.
+ */
+static int ext4_get_fsinfo(struct dentry *dentry, struct fsinfo *f,
+ unsigned flags)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ struct ext4_super_block *es = sbi->s_es;
+ struct inode *inode = d_inode(dentry);
+ struct ext4_inode *raw_inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+
+ strcpy(f->f_volume_name, es->s_volume_name);
+
+ f->f_mask = FSINFO_FSID | FSINFO_VOLUME_NAME;
+ f->f_supported_ioc_flags = EXT4_FL_USER_VISIBLE;
+
+ f->f_min_time = S32_MIN;
+ f->f_max_time = S32_MAX;
+
+ if (EXT4_FITS_IN_INODE(raw_inode, ei, i_ctime_extra))
+ f->f_ctime_gran_exponent = -9;
+ if (EXT4_FITS_IN_INODE(raw_inode, ei, i_mtime_extra))
+ f->f_mtime_gran_exponent = -9;
+ if (EXT4_FITS_IN_INODE(raw_inode, ei, i_atime_extra)) {
+ f->f_atime_gran_exponent = -9;
+ f->f_max_time += ((1 << EXT4_EPOCH_BITS) - 1) * 0x100000000LL;
+ }
+ if (EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime_extra))
+ f->f_btime_gran_exponent = -9;
+
+ return vfs_get_fsinfo_from_statfs(dentry, f, flags);
+}
+
/* Helper function for writing quotas on sync - we need to start transaction
* before quota file is locked for write. Otherwise the are possible deadlocks:
* Process 1 Process 2
--
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