On Wed, 22 May 2013 10:23:47 +0400, Vyacheslav Dubeyko wrote:
> 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.
Nack.
Please stop switching atomic_t and atomic64_t in nilfs with heavy use
of ifdef macros and inline functions. It is seriously hurting the
readability and simplicity of source code.
Consider using "atomic_long_t", and please try to keep the patch
simple.
In my opinion, mi_desc_blocks_count is no longer needed because
nilfs_bmap_last_key is not so heavy. But, I don't deny adding this
counter.
> 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?
Yes, looks like they should be replaced with atomic_long_t type
counters (with a separate patch, of course).
Regards,
Ryusuke Konishi
> 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;
<snip>
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