Hi Ryusuke,
This is fourth version of the patch. I reworked representation of
mi_desc_blocks_count because I think that using this field is good
solution for calculation of max entries count.
By the way, I see that it is used atomic_t type for representation
of inodes_count and blocks_count fields in nilfs_root structure.
Maybe it makes sense to rework representation of these fields too.
What do you think?
v3->v4
* The desc_blocks value is represented by unsigned long type.
* The nilfs_palloc_count_desc_blocks() method is simplified.
* The mi_desc_blocks_count field of nilfs_mdt_info structure
is represented as atomic64_t for the case of CONFIG_64BIT and
as atomic_t for other cases.
v2->v3
* Trivial BUG_ON checks were removed.
* Whole calculation algorithm was moved into
nilfs_palloc_count_max_entries() method.
* Improve error processing in the code.
* The nilfs_palloc_mdt_file_can_grow() method was simplified.
* The nilfs_ifile_count_free_inodes() method was simplified.
v1->v2
* Change __statfs_word on u64 type.
* Rename nilfs_count_free_inodes() into nilfs_ifile_count_free_inodes()
method.
* Introduce auxiliary functions: nilfs_palloc_count_max_entries(),
nilfs_palloc_count_desc_blocks(), nilfs_palloc_mdt_file_can_grow().
* Rework processing of returned error from nilfs_ifile_count_free_inodes()
in nilfs_statfs().
With the best regards,
Vyacheslav Dubeyko.
---
From: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
Subject: [PATCH v4] nilfs2: implement calculation of free inodes count
Currently, NILFS2 returns 0 as free inodes count (f_ffree) and
current used inodes count as total file nodes in file system
(f_files):
df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/loop0 2 2 0 100% /mnt/nilfs2
This patch implements real calculation of free inodes count.
First of all, it is calculated total file nodes in file system
as (desc_blocks_count * groups_per_desc_block * entries_per_group).
Then, it is calculated free inodes count as difference the total
file nodes and used inodes count. As a result, we have such output
for NILFS2:
df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/loop0 4194304 2114701 2079603 51% /mnt/nilfs2
Reported-by: Clemens Eisserer <linuxhippy@xxxxxxxxx>
Signed-off-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Tested-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
---
fs/nilfs2/alloc.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/nilfs2/alloc.h | 2 ++
fs/nilfs2/ifile.c | 22 +++++++++++++++
fs/nilfs2/ifile.h | 2 +-
fs/nilfs2/mdt.h | 26 ++++++++++++++++++
fs/nilfs2/super.c | 25 +++++++++++++++--
6 files changed, 152 insertions(+), 3 deletions(-)
diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
index eed4d7b..e5ea7b3 100644
--- a/fs/nilfs2/alloc.c
+++ b/fs/nilfs2/alloc.c
@@ -80,6 +80,13 @@ int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned entry_size)
mi->mi_blocks_per_group + 1;
/* Number of blocks per descriptor including the
descriptor block */
+ nilfs_mdt_set_desc_blocks(mi, 1);
+ /*
+ * The field mi_desc_blocks_count is used for
+ * storing knowledge about current count of
+ * desciptor blocks. Initially, it is initialized
+ * by one.
+ */
return 0;
}
@@ -398,6 +405,77 @@ nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
}
/**
+ * nilfs_palloc_count_desc_blocks - count descriptor blocks number
+ * @inode: inode of metadata file using this allocator
+ * @desc_blocks: descriptor blocks number [out]
+ */
+static int nilfs_palloc_count_desc_blocks(struct inode *inode,
+ unsigned long *desc_blocks)
+{
+ unsigned long blknum;
+ int ret;
+
+ ret = nilfs_bmap_last_key(NILFS_I(inode)->i_bmap, &blknum);
+ if (likely(!ret))
+ *desc_blocks = DIV_ROUND_UP(
+ blknum, NILFS_MDT(inode)->mi_blocks_per_desc_block);
+ return ret;
+}
+
+/**
+ * nilfs_palloc_mdt_file_can_grow - check potential opportunity for
+ * MDT file growing
+ * @inode: inode of metadata file using this allocator
+ * @desc_blocks: known current descriptor blocks count
+ */
+static inline bool nilfs_palloc_mdt_file_can_grow(struct inode *inode,
+ unsigned long desc_blocks)
+{
+ return (nilfs_palloc_groups_per_desc_block(inode) * desc_blocks) <
+ nilfs_palloc_groups_count(inode);
+}
+
+/**
+ * nilfs_palloc_count_max_entries - count max number of entries that can be
+ * described by descriptor blocks count
+ * @inode: inode of metadata file using this allocator
+ * @nused: current number of used entries
+ * @nmaxp: max number of entries [out]
+ */
+int nilfs_palloc_count_max_entries(struct inode *inode, u64 nused, u64 *nmaxp)
+{
+ unsigned long desc_blocks;
+ u64 entries_per_desc_block, nmax;
+ int err;
+
+ desc_blocks = nilfs_mdt_read_desc_blocks(NILFS_MDT(inode));
+ entries_per_desc_block = (u64)nilfs_palloc_entries_per_group(inode) *
+ nilfs_palloc_groups_per_desc_block(inode);
+
+ nmax = entries_per_desc_block * desc_blocks;
+ if (nused >= nmax) {
+ err = nilfs_palloc_count_desc_blocks(inode, &desc_blocks);
+ if (unlikely(err))
+ return err;
+
+ nmax = entries_per_desc_block * desc_blocks;
+ if (nused == nmax &&
+ nilfs_palloc_mdt_file_can_grow(inode,
+ desc_blocks)) {
+ nmax += entries_per_desc_block;
+ ++desc_blocks;
+ }
+
+ nilfs_mdt_set_desc_blocks(NILFS_MDT(inode), desc_blocks);
+
+ if (nused > nmax)
+ return -ERANGE;
+ }
+ *nmaxp = nmax;
+ return 0;
+}
+
+/**
* nilfs_palloc_prepare_alloc_entry - prepare to allocate a persistent object
* @inode: inode of metadata file using this allocator
* @req: nilfs_palloc_req structure exchanged for the allocation
diff --git a/fs/nilfs2/alloc.h b/fs/nilfs2/alloc.h
index fb72381..4bd6451 100644
--- a/fs/nilfs2/alloc.h
+++ b/fs/nilfs2/alloc.h
@@ -48,6 +48,8 @@ int nilfs_palloc_get_entry_block(struct inode *, __u64, int,
void *nilfs_palloc_block_get_entry(const struct inode *, __u64,
const struct buffer_head *, void *);
+int nilfs_palloc_count_max_entries(struct inode *, u64, u64 *);
+
/**
* nilfs_palloc_req - persistent allocator request and reply
* @pr_entry_nr: entry number (vblocknr or inode number)
diff --git a/fs/nilfs2/ifile.c b/fs/nilfs2/ifile.c
index d8e65bd..d788a59 100644
--- a/fs/nilfs2/ifile.c
+++ b/fs/nilfs2/ifile.c
@@ -160,6 +160,28 @@ int nilfs_ifile_get_inode_block(struct inode *ifile, ino_t ino,
}
/**
+ * nilfs_ifile_count_free_inodes - calculate free inodes count
+ * @ifile: ifile inode
+ * @nmaxinodes: current maximum of available inodes count [out]
+ * @nfreeinodes: free inodes count [out]
+ */
+int nilfs_ifile_count_free_inodes(struct inode *ifile,
+ u64 *nmaxinodes, u64 *nfreeinodes)
+{
+ u64 nused;
+ int err;
+
+ *nmaxinodes = 0;
+ *nfreeinodes = 0;
+
+ nused = atomic_read(&NILFS_I(ifile)->i_root->inodes_count);
+ err = nilfs_palloc_count_max_entries(ifile, nused, nmaxinodes);
+ if (likely(!err))
+ *nfreeinodes = *nmaxinodes - nused;
+ return err;
+}
+
+/**
* nilfs_ifile_read - read or get ifile inode
* @sb: super block instance
* @root: root object
diff --git a/fs/nilfs2/ifile.h b/fs/nilfs2/ifile.h
index 59b6f2b..e9ceb27 100644
--- a/fs/nilfs2/ifile.h
+++ b/fs/nilfs2/ifile.h
@@ -48,7 +48,7 @@ static inline void nilfs_ifile_unmap_inode(struct inode *ifile, ino_t ino,
int nilfs_ifile_create_inode(struct inode *, ino_t *, struct buffer_head **);
int nilfs_ifile_delete_inode(struct inode *, ino_t);
int nilfs_ifile_get_inode_block(struct inode *, ino_t, struct buffer_head **);
-
+int nilfs_ifile_count_free_inodes(struct inode *, u64 *, u64 *);
int nilfs_ifile_read(struct super_block *sb, struct nilfs_root *root,
size_t inode_size, struct nilfs_inode *raw_inode,
struct inode **inodep);
diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
index ab172e8..bcd11bf 100644
--- a/fs/nilfs2/mdt.h
+++ b/fs/nilfs2/mdt.h
@@ -53,6 +53,7 @@ struct nilfs_shadow_map {
* @mi_shadow: shadow of bmap and page caches
* @mi_blocks_per_group: number of blocks in a group
* @mi_blocks_per_desc_block: number of blocks per descriptor block
+ * @mi_desc_blocks_count: number of descriptor blocks
*/
struct nilfs_mdt_info {
struct rw_semaphore mi_sem;
@@ -64,8 +65,33 @@ struct nilfs_mdt_info {
struct nilfs_shadow_map *mi_shadow;
unsigned long mi_blocks_per_group;
unsigned long mi_blocks_per_desc_block;
+#ifdef CONFIG_64BIT
+ atomic64_t mi_desc_blocks_count;
+#else
+ atomic_t mi_desc_blocks_count;
+#endif /* CONFIG_64BIT */
};
+static inline
+void nilfs_mdt_set_desc_blocks(struct nilfs_mdt_info *mi, unsigned long value)
+{
+#ifdef CONFIG_64BIT
+ atomic64_set(&mi->mi_desc_blocks_count, value);
+#else
+ atomic_set(&mi->mi_desc_blocks_count, value);
+#endif
+}
+
+static inline
+unsigned long nilfs_mdt_read_desc_blocks(struct nilfs_mdt_info *mi)
+{
+#ifdef CONFIG_64BIT
+ return atomic64_read(&mi->mi_desc_blocks_count);
+#else
+ return atomic_read(&mi->mi_desc_blocks_count);
+#endif
+}
+
static inline struct nilfs_mdt_info *NILFS_MDT(const struct inode *inode)
{
return inode->i_private;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index c7d1f9f..acd110f 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -609,6 +609,7 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
unsigned long overhead;
unsigned long nrsvblocks;
sector_t nfreeblocks;
+ u64 nmaxinodes, nfreeinodes;
int err;
/*
@@ -633,14 +634,34 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
if (unlikely(err))
return err;
+ err = nilfs_ifile_count_free_inodes(root->ifile,
+ &nmaxinodes, &nfreeinodes);
+ if (unlikely(err)) {
+ printk(KERN_WARNING
+ "NILFS warning: fail to count free inodes: err %d.\n",
+ err);
+ if (err == -ERANGE) {
+ /*
+ * If nilfs_palloc_count_max_entries() returns
+ * -ERANGE error code then we simply treat
+ * curent inodes count as maximum possible and
+ * zero as free inodes value.
+ */
+ nmaxinodes = atomic_read(&root->inodes_count);
+ nfreeinodes = 0;
+ err = 0;
+ } else
+ return err;
+ }
+
buf->f_type = NILFS_SUPER_MAGIC;
buf->f_bsize = sb->s_blocksize;
buf->f_blocks = blocks - overhead;
buf->f_bfree = nfreeblocks;
buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
(buf->f_bfree - nrsvblocks) : 0;
- buf->f_files = atomic_read(&root->inodes_count);
- buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
+ buf->f_files = nmaxinodes;
+ buf->f_ffree = nfreeinodes;
buf->f_namelen = NILFS_NAME_LEN;
buf->f_fsid.val[0] = (u32)id;
buf->f_fsid.val[1] = (u32)(id >> 32);
--
1.7.9.5
--
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