On Mon, 13 May 2013 15:54:51 +0400, Vyacheslav Dubeyko wrote:
> Hi Ryusuke,
>
> This is second version of the patch.
>
> 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 v2] 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>
> CC: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
> Tested-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
I will comment inline.
First of all, please insert CR/LF properly also for the change log description:
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,
...
> ---
> fs/nilfs2/alloc.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/nilfs2/alloc.h | 4 +++
> fs/nilfs2/ifile.c | 52 ++++++++++++++++++++++++++++++++
> fs/nilfs2/ifile.h | 2 ++
> fs/nilfs2/mdt.h | 2 ++
> fs/nilfs2/super.c | 15 ++++++++--
> 6 files changed, 158 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
> index eed4d7b..519600e 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 */
> + atomic_set(&mi->mi_desc_blocks_count, 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 +405,84 @@ nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
> }
>
> /**
> + * nilfs_palloc_count_max_entries - count max number of entries that can be
> + * described by @desc_blocks
> + * @inode: inode of metadata file using this allocator
> + * @desc_blocks: descriptor blocks count
> + */
> +u64 nilfs_palloc_count_max_entries(struct inode *inode,
> + unsigned int desc_blocks)
The logical upper limit of descriptor block count is 2 ^ 43 (in the
case of 64-bit architecture), so the desc_blocks argument should have
unsigned long type.
> +{
> + unsigned long ngroups;
> + unsigned long groups_per_desc_block;
> + unsigned long entries_per_group;
> + unsigned long entries_per_desc_block;
> +
> + BUG_ON(!inode);
Do not insert trivial BUG_ON check like this. This inode never
becomes NULL.
> +
> + ngroups = nilfs_palloc_groups_count(inode);
> + groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);
> + entries_per_group = nilfs_palloc_entries_per_group(inode);
> + entries_per_desc_block = groups_per_desc_block * entries_per_group;
> +
> + return entries_per_desc_block * (u64)desc_blocks;
> +}
No, I meant moving whole calculation algorithm to alloc.c as follows:
int nilfs_palloc_count_max_entries(struct inode *inode, u64 nused, u64 *nmax)
{
unsigned long desc_blocks;
u64 entries_per_desc_block, nmax;
desc_blocks = atomic_read(&NILFS_MDT(inode)->mi_desc_blocks_count);
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,
&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;
}
atomic_set(&NILFS_MDT(inode)->mi_desc_blocks_count, desc_blocks);
if (nused > nmax)
return -ERANGE;
}
*nmaxp = nmax;
return 0;
}
> +/**
> + * nilfs_palloc_count_desc_blocks - count descriptor blocks number
> + * @inode: inode of metadata file using this allocator
> + * @start_desc_blks: known current descriptor blocks count
> + */
> +unsigned int nilfs_palloc_count_desc_blocks(struct inode *inode,
> + unsigned int start_desc_blks)
> +{
> + unsigned long ngroups;
> + unsigned long groups_per_desc_block;
> + struct buffer_head *desc_bh;
> + unsigned long i;
> + unsigned int desc_blocks = start_desc_blks;
> + int err;
> +
> + BUG_ON(!inode);
Ditto.
> +
> + ngroups = nilfs_palloc_groups_count(inode);
> + groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);
> + i = groups_per_desc_block * (unsigned long)desc_blocks;
> +
> + for (; i < ngroups; i += groups_per_desc_block) {
> + err = nilfs_palloc_get_desc_block(inode, i, 0, &desc_bh);
This index variable i would be better if named "group":
...
group = groups_per_desc_block * desc_blocks;
for (; group < ngroups; group += groups_per_desc_block) {
err = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
> + if (err)
> + break;
> + else
> + desc_blocks++;
> + brelse(desc_bh);
Expected termination code of nilfs_palloc_get_desc_block() is -ENOENT,
which means no descriptor block found, but you should consider that
the function may return critical errors like -EIO or -ENOMEM. So,
these should be:
err = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
if (err) {
if (err == -ENOENT)
break;
return err;
}
desc_blocks++;
brelse(desc_bh);
Inevitably, the function should take status code as its return value:
int nilfs_palloc_count_desc_blocks(struct inode *inode,
unsigned long start_desc_blks,
unsigned long *desc_blocks);
> + }
> +
> + return desc_blocks;
> +}
> +
> +/**
> + * 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
> + */
> +bool nilfs_palloc_mdt_file_can_grow(struct inode *inode,
> + unsigned int desc_blocks)
> +{
> + unsigned long ngroups;
> + unsigned long groups_per_desc_block;
> +
> + BUG_ON(!inode);
Ditto.
> +
> + ngroups = nilfs_palloc_groups_count(inode);
> + groups_per_desc_block = nilfs_palloc_groups_per_desc_block(inode);
> +
> + return (groups_per_desc_block * (u64)desc_blocks) < ngroups;
> +}
Write more simply, like below, please.
static 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_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..db1d222 100644
> --- a/fs/nilfs2/alloc.h
> +++ b/fs/nilfs2/alloc.h
> @@ -48,6 +48,10 @@ 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 *);
>
> +u64 nilfs_palloc_count_max_entries(struct inode *, unsigned int);
> +unsigned int nilfs_palloc_count_desc_blocks(struct inode *, unsigned int);
> +bool nilfs_palloc_mdt_file_can_grow(struct inode *, unsigned int);
> +
> /**
> * 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..fe0e02f 100644
> --- a/fs/nilfs2/ifile.c
> +++ b/fs/nilfs2/ifile.c
> @@ -160,6 +160,58 @@ int nilfs_ifile_get_inode_block(struct inode *ifile, ino_t ino,
> }
>
> /**
> + * nilfs_ifile_count_free_inodes - calculate free inodes count
> + * @root: root object
> + * @nmaxinodes: current maximum of available inodes count [out]
> + * @nfreeinodes: free inodes count [out]
> + */
> +int nilfs_ifile_count_free_inodes(struct nilfs_root *root,
> + u64 *nmaxinodes,
> + u64 *nfreeinodes)
> +{
> + struct inode *ifile;
> + unsigned int desc_blocks;
> + u64 nused, nmax;
> +
> + BUG_ON(!root || !nfreeinodes || !nmaxinodes);
Ditto. All these BUG_ON checks are useless.
The first arugment of this function shoude be ifile inode like other
functions (nilfs_ifile_read is the only special case) since the
nilfs_root object "root" can be obtainable from the ifile inode
(e.g. "NILFS_I(ifile)->i_root").
With the nilfs_palloc_count_max_entries() function above, you can
eliminate algorithm depending on the persistent object allocator from
this function, and can simplify the function:
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;
}
> +
> + ifile = root->ifile;
> + *nmaxinodes = 0;
> + *nfreeinodes = 0;
> +
> + nused = atomic_read(&root->inodes_count);
> + desc_blocks =
> + atomic_read(&NILFS_IFILE_I(ifile)->mi.mi_desc_blocks_count);
> + nmax = nilfs_palloc_count_max_entries(ifile, desc_blocks);
> +
> + if (nused >= nmax) {
> + desc_blocks =
> + nilfs_palloc_count_desc_blocks(ifile, desc_blocks);
> + nmax = nilfs_palloc_count_max_entries(ifile, desc_blocks);
> +
> + if (nused == nmax) {
> + if (nilfs_palloc_mdt_file_can_grow(ifile,
> + desc_blocks)) {
> + nmax =
> + nilfs_palloc_count_max_entries(ifile,
> + ++desc_blocks);
> + }
> + }
> +
> + atomic_set(&NILFS_IFILE_I(ifile)->mi.mi_desc_blocks_count,
> + desc_blocks);
> +
> + if (nused > nmax)
> + return -ERANGE;
> + }
> +
> + *nmaxinodes = nmax;
> + *nfreeinodes = nmax - nused;
> +
> + return 0;
> +}
> +
> +/**
> * 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..aee5ab01 100644
> --- a/fs/nilfs2/ifile.h
> +++ b/fs/nilfs2/ifile.h
> @@ -49,6 +49,8 @@ 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 nilfs_root *, 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..c01b6fb 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;
> @@ -64,6 +65,7 @@ struct nilfs_mdt_info {
> struct nilfs_shadow_map *mi_shadow;
> unsigned long mi_blocks_per_group;
> unsigned long mi_blocks_per_desc_block;
> + atomic_t mi_desc_blocks_count;
> };
>
> static inline struct nilfs_mdt_info *NILFS_MDT(const struct inode *inode)
> diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
> index c7d1f9f..33f427a 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 +634,24 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
> if (unlikely(err))
> return err;
>
> + err = nilfs_ifile_count_free_inodes(root, &nmaxinodes, &nfreeinodes);
> + if (unlikely(err)) {
> + printk(KERN_WARNING
> + "NILFS warning: fail to count free inodes: err %d.\n",
> + err);
> + err = 0;
> + nmaxinodes = atomic_read(&root->inodes_count);
> + nfreeinodes = 0;
> + }
I meant critical error like -EIO or -ENOMEM still should be returned
to user space. Do not kill all error codes like this. I think only
-ERANGE should be ignored because it's an internal error code that
you made in the routine.
With regards,
Ryusuke Konishi
> 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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