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Re: [PATCH 2/6] ext4: refactor ext4_fallocate code

To: Lukas Czerner <lczerner@xxxxxxxxxx>
Subject: Re: [PATCH 2/6] ext4: refactor ext4_fallocate code
From: jon ernst <jonernst07@xxxxxxxxx>
Date: Tue, 18 Feb 2014 08:25:25 +0000
Cc: "linux-ext4@xxxxxxxxxxxxxxx List" <linux-ext4@xxxxxxxxxxxxxxx>, "Theodore Ts'o" <tytso@xxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
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seems "int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,"
should be "static int ext4_alloc_file_blocks(struct file *file,
ext4_lblk_t offset,"


Jon

On Mon, Feb 17, 2014 at 3:08 PM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote:
> Move block allocation out of the ext4_fallocate into separate function
> called ext4_alloc_file_blocks(). This will allow us to use the same
> allocation code for other allocation operations such as zero range which
> is commit in the next patch.
>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> ---
>  fs/ext4/extents.c | 127 
> +++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 73 insertions(+), 54 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 6a52851..2d68a46 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4513,6 +4513,64 @@ retry:
>         ext4_std_error(inode->i_sb, err);
>  }
>
> +int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,
> +                          ext4_lblk_t len, int flags, int mode)
> +{
> +       struct inode *inode = file_inode(file);
> +       handle_t *handle;
> +       int ret = 0;
> +       int ret2 = 0;
> +       int retries = 0;
> +       struct ext4_map_blocks map;
> +       unsigned int credits;
> +
> +       map.m_lblk = offset;
> +       /*
> +        * Don't normalize the request if it can fit in one extent so
> +        * that it doesn't get unnecessarily split into multiple
> +        * extents.
> +        */
> +       if (len <= EXT_UNINIT_MAX_LEN)
> +               flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
> +
> +       /*
> +        * credits to insert 1 extent into extent tree
> +        */
> +       credits = ext4_chunk_trans_blocks(inode, len);
> +
> +retry:
> +       while (ret >= 0 && ret < len) {
> +               map.m_lblk = map.m_lblk + ret;
> +               map.m_len = len = len - ret;
> +               handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
> +                                           credits);
> +               if (IS_ERR(handle)) {
> +                       ret = PTR_ERR(handle);
> +                       break;
> +               }
> +               ret = ext4_map_blocks(handle, inode, &map, flags);
> +               if (ret <= 0) {
> +                       ext4_debug("inode #%lu: block %u: len %u: "
> +                                  "ext4_ext_map_blocks returned %d",
> +                                  inode->i_ino, map.m_lblk,
> +                                  map.m_len, ret);
> +                       ext4_mark_inode_dirty(handle, inode);
> +                       ret2 = ext4_journal_stop(handle);
> +                       break;
> +               }
> +               ret2 = ext4_journal_stop(handle);
> +               if (ret2)
> +                       break;
> +       }
> +       if (ret == -ENOSPC &&
> +                       ext4_should_retry_alloc(inode->i_sb, &retries)) {
> +               ret = 0;
> +               goto retry;
> +       }
> +
> +       return ret > 0 ? ret2 : ret;
> +}
> +
>  /*
>   * preallocate space for a file. This implements ext4's fallocate file
>   * operation, which gets called from sys_fallocate system call.
> @@ -4527,11 +4585,9 @@ long ext4_fallocate(struct file *file, int mode, 
> loff_t offset, loff_t len)
>         loff_t new_size = 0;
>         unsigned int max_blocks;
>         int ret = 0;
> -       int ret2 = 0;
> -       int retries = 0;
>         int flags;
> -       struct ext4_map_blocks map;
> -       unsigned int credits, blkbits = inode->i_blkbits;
> +       ext4_lblk_t lblk;
> +       unsigned int blkbits = inode->i_blkbits;
>
>         /* Return error if mode is not supported */
>         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
> @@ -4552,17 +4608,18 @@ long ext4_fallocate(struct file *file, int mode, 
> loff_t offset, loff_t len)
>                 return -EOPNOTSUPP;
>
>         trace_ext4_fallocate_enter(inode, offset, len, mode);
> -       map.m_lblk = offset >> blkbits;
> +       lblk = offset >> blkbits;
>         /*
>          * We can't just convert len to max_blocks because
>          * If blocksize = 4096 offset = 3072 and len = 2048
>          */
>         max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
> -               - map.m_lblk;
> -       /*
> -        * credits to insert 1 extent into extent tree
> -        */
> -       credits = ext4_chunk_trans_blocks(inode, max_blocks);
> +               - lblk;
> +
> +       flags = EXT4_GET_BLOCKS_CREATE_UNINIT_EXT;
> +       if (mode & FALLOC_FL_KEEP_SIZE)
> +               flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
> +
>         mutex_lock(&inode->i_mutex);
>
>         if (!(mode & FALLOC_FL_KEEP_SIZE) &&
> @@ -4573,46 +4630,9 @@ long ext4_fallocate(struct file *file, int mode, 
> loff_t offset, loff_t len)
>                         goto out;
>         }
>
> -       flags = EXT4_GET_BLOCKS_CREATE_UNINIT_EXT;
> -       if (mode & FALLOC_FL_KEEP_SIZE)
> -               flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
> -       /*
> -        * Don't normalize the request if it can fit in one extent so
> -        * that it doesn't get unnecessarily split into multiple
> -        * extents.
> -        */
> -       if (len <= EXT_UNINIT_MAX_LEN << blkbits)
> -               flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
> -
> -retry:
> -       while (ret >= 0 && ret < max_blocks) {
> -               map.m_lblk = map.m_lblk + ret;
> -               map.m_len = max_blocks = max_blocks - ret;
> -               handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
> -                                           credits);
> -               if (IS_ERR(handle)) {
> -                       ret = PTR_ERR(handle);
> -                       break;
> -               }
> -               ret = ext4_map_blocks(handle, inode, &map, flags);
> -               if (ret <= 0) {
> -                       ext4_debug("inode #%lu: block %u: len %u: "
> -                                  "ext4_ext_map_blocks returned %d",
> -                                  inode->i_ino, map.m_lblk,
> -                                  map.m_len, ret);
> -                       ext4_mark_inode_dirty(handle, inode);
> -                       ret2 = ext4_journal_stop(handle);
> -                       break;
> -               }
> -               ret2 = ext4_journal_stop(handle);
> -               if (ret2)
> -                       break;
> -       }
> -       if (ret == -ENOSPC &&
> -                       ext4_should_retry_alloc(inode->i_sb, &retries)) {
> -               ret = 0;
> -               goto retry;
> -       }
> +       ret = ext4_alloc_file_blocks(file, lblk, max_blocks, flags, mode);
> +       if (ret)
> +               goto out;
>
>         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
>         if (IS_ERR(handle))
> @@ -4620,7 +4640,7 @@ retry:
>
>         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
>
> -       if (ret > 0 && new_size) {
> +       if (!ret && new_size) {
>                 if (new_size > i_size_read(inode))
>                         i_size_write(inode, new_size);
>                 if (new_size > EXT4_I(inode)->i_disksize)
> @@ -4633,9 +4653,8 @@ retry:
>         ext4_journal_stop(handle);
>  out:
>         mutex_unlock(&inode->i_mutex);
> -       trace_ext4_fallocate_exit(inode, offset, max_blocks,
> -                               ret > 0 ? ret2 : ret);
> -       return ret > 0 ? ret2 : ret;
> +       trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
> +       return ret;
>  }
>
>  /*
> --
> 1.8.3.1
>
> --
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