Re: [PATCH 11/12] ext4: fix the number of credits needed for acl ops with inline data

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Quick question from a n00b.

What are "credits"?

I imagine I'm not the only onlooker curious about ti either.

On Sun, Feb 10, 2013 at 5:42 AM, Tao Ma <tm@xxxxxx> wrote:
> On 02/10/2013 05:53 AM, Theodore Ts'o wrote:
>> Operations which modify extended attributes may need extra journal
>> credits if inline data is used, since there is a chance that some
>> extended attributes may need to get pushed to an external attribute
>> block.
>>
>> Changes to reflect this was made in xattr.c, but they were missed in
>> fs/ext4/acl.c.  To fix this, abstract the calculation of the number of
>> credits needed for xattr operations to an inline function defined in
>> ext4_jbd2.h, and use it in acl.c and xattr.c.
> Oh, yes, I forgot about the acl.
>
> Reviewed-by: Tao Ma <boyu.mt@xxxxxxxxxx>
>
> Thanks,
> Tao
>>
>> Also move the function declarations used in inline.c from xattr.h
>> (where they are non-obviously hidden, and caused problems since
>> ext4_jbd2.h needs to use the function ext4_has_inline_data), and move
>> them to ext4.h.
>>
>> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
>> Cc: Tao Ma <boyu.mt@xxxxxxxxxx>
>> ---
>>  fs/ext4/acl.c       |  4 +--
>>  fs/ext4/ext4.h      | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  fs/ext4/ext4_jbd2.h | 14 +++++++++++
>>  fs/ext4/xattr.c     |  9 +------
>>  fs/ext4/xattr.h     | 68 ---------------------------------------------------
>>  5 files changed, 87 insertions(+), 78 deletions(-)
>>
>> diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
>> index 406cf8b..39a54a0 100644
>> --- a/fs/ext4/acl.c
>> +++ b/fs/ext4/acl.c
>> @@ -325,7 +325,7 @@ ext4_acl_chmod(struct inode *inode)
>>               return error;
>>  retry:
>>       handle = ext4_journal_start(inode, EXT4_HT_XATTR,
>> -                     EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
>> +                                 ext4_jbd2_credits_xattr(inode));
>>       if (IS_ERR(handle)) {
>>               error = PTR_ERR(handle);
>>               ext4_std_error(inode->i_sb, error);
>> @@ -423,7 +423,7 @@ ext4_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
>>
>>  retry:
>>       handle = ext4_journal_start(inode, EXT4_HT_XATTR,
>> -                                 EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
>> +                                 ext4_jbd2_credits_xattr(inode));
>>       if (IS_ERR(handle)) {
>>               error = PTR_ERR(handle);
>>               goto release_and_out;
>> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
>> index c2c64da..9897cdf 100644
>> --- a/fs/ext4/ext4.h
>> +++ b/fs/ext4/ext4.h
>> @@ -2443,6 +2443,75 @@ extern const struct file_operations ext4_file_operations;
>>  extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
>>  extern void ext4_unwritten_wait(struct inode *inode);
>>
>> +/* inline.c */
>> +extern int ext4_has_inline_data(struct inode *inode);
>> +extern int ext4_get_inline_size(struct inode *inode);
>> +extern int ext4_get_max_inline_size(struct inode *inode);
>> +extern int ext4_find_inline_data_nolock(struct inode *inode);
>> +extern void ext4_write_inline_data(struct inode *inode,
>> +                                struct ext4_iloc *iloc,
>> +                                void *buffer, loff_t pos,
>> +                                unsigned int len);
>> +extern int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
>> +                                 unsigned int len);
>> +extern int ext4_init_inline_data(handle_t *handle, struct inode *inode,
>> +                              unsigned int len);
>> +extern int ext4_destroy_inline_data(handle_t *handle, struct inode *inode);
>> +
>> +extern int ext4_readpage_inline(struct inode *inode, struct page *page);
>> +extern int ext4_try_to_write_inline_data(struct address_space *mapping,
>> +                                      struct inode *inode,
>> +                                      loff_t pos, unsigned len,
>> +                                      unsigned flags,
>> +                                      struct page **pagep);
>> +extern int ext4_write_inline_data_end(struct inode *inode,
>> +                                   loff_t pos, unsigned len,
>> +                                   unsigned copied,
>> +                                   struct page *page);
>> +extern struct buffer_head *
>> +ext4_journalled_write_inline_data(struct inode *inode,
>> +                               unsigned len,
>> +                               struct page *page);
>> +extern int ext4_da_write_inline_data_begin(struct address_space *mapping,
>> +                                        struct inode *inode,
>> +                                        loff_t pos, unsigned len,
>> +                                        unsigned flags,
>> +                                        struct page **pagep,
>> +                                        void **fsdata);
>> +extern int ext4_da_write_inline_data_end(struct inode *inode, loff_t pos,
>> +                                      unsigned len, unsigned copied,
>> +                                      struct page *page);
>> +extern int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
>> +                                  struct inode *inode);
>> +extern int ext4_try_create_inline_dir(handle_t *handle,
>> +                                   struct inode *parent,
>> +                                   struct inode *inode);
>> +extern int ext4_read_inline_dir(struct file *filp,
>> +                             void *dirent, filldir_t filldir,
>> +                             int *has_inline_data);
>> +extern struct buffer_head *ext4_find_inline_entry(struct inode *dir,
>> +                                     const struct qstr *d_name,
>> +                                     struct ext4_dir_entry_2 **res_dir,
>> +                                     int *has_inline_data);
>> +extern int ext4_delete_inline_entry(handle_t *handle,
>> +                                 struct inode *dir,
>> +                                 struct ext4_dir_entry_2 *de_del,
>> +                                 struct buffer_head *bh,
>> +                                 int *has_inline_data);
>> +extern int empty_inline_dir(struct inode *dir, int *has_inline_data);
>> +extern struct buffer_head *ext4_get_first_inline_block(struct inode *inode,
>> +                                     struct ext4_dir_entry_2 **parent_de,
>> +                                     int *retval);
>> +extern int ext4_inline_data_fiemap(struct inode *inode,
>> +                                struct fiemap_extent_info *fieinfo,
>> +                                int *has_inline);
>> +extern int ext4_try_to_evict_inline_data(handle_t *handle,
>> +                                      struct inode *inode,
>> +                                      int needed);
>> +extern void ext4_inline_data_truncate(struct inode *inode, int *has_inline);
>> +
>> +extern int ext4_convert_inline_data(struct inode *inode);
>> +
>>  /* namei.c */
>>  extern const struct inode_operations ext4_dir_inode_operations;
>>  extern const struct inode_operations ext4_special_inode_operations;
>> @@ -2539,6 +2608,7 @@ extern void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp);
>>  extern int ext4_mmp_csum_verify(struct super_block *sb,
>>                               struct mmp_struct *mmp);
>>
>> +
>>  /* BH_Uninit flag: blocks are allocated but uninitialized on disk */
>>  enum ext4_state_bits {
>>       BH_Uninit       /* blocks are allocated but uninitialized on disk */
>> diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
>> index c1fc2dc..4c216b1 100644
>> --- a/fs/ext4/ext4_jbd2.h
>> +++ b/fs/ext4/ext4_jbd2.h
>> @@ -104,6 +104,20 @@
>>  #define EXT4_MAXQUOTAS_INIT_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_INIT_BLOCKS(sb))
>>  #define EXT4_MAXQUOTAS_DEL_BLOCKS(sb) (MAXQUOTAS*EXT4_QUOTA_DEL_BLOCKS(sb))
>>
>> +static inline int ext4_jbd2_credits_xattr(struct inode *inode)
>> +{
>> +     int credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb);
>> +
>> +     /*
>> +      * In case of inline data, we may push out the data to a block,
>> +      * so we need to reserve credits for this eventuality
>> +      */
>> +     if (ext4_has_inline_data(inode))
>> +             credits += ext4_writepage_trans_blocks(inode) + 1;
>> +     return credits;
>> +}
>> +
>> +
>>  /*
>>   * Ext4 handle operation types -- for logging purposes
>>   */
>> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
>> index 2efc560..cc31da0 100644
>> --- a/fs/ext4/xattr.c
>> +++ b/fs/ext4/xattr.c
>> @@ -1165,16 +1165,9 @@ ext4_xattr_set(struct inode *inode, int name_index, const char *name,
>>  {
>>       handle_t *handle;
>>       int error, retries = 0;
>> -     int credits = EXT4_DATA_TRANS_BLOCKS(inode->i_sb);
>> +     int credits = ext4_jbd2_credits_xattr(inode);
>>
>>  retry:
>> -     /*
>> -      * In case of inline data, we may push out the data to a block,
>> -      * So reserve the journal space first.
>> -      */
>> -     if (ext4_has_inline_data(inode))
>> -             credits += ext4_writepage_trans_blocks(inode) + 1;
>> -
>>       handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
>>       if (IS_ERR(handle)) {
>>               error = PTR_ERR(handle);
>> diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h
>> index 69eda78..aa25deb 100644
>> --- a/fs/ext4/xattr.h
>> +++ b/fs/ext4/xattr.h
>> @@ -125,74 +125,6 @@ extern int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
>>                                      struct ext4_xattr_info *i,
>>                                      struct ext4_xattr_ibody_find *is);
>>
>> -extern int ext4_has_inline_data(struct inode *inode);
>> -extern int ext4_get_inline_size(struct inode *inode);
>> -extern int ext4_get_max_inline_size(struct inode *inode);
>> -extern int ext4_find_inline_data_nolock(struct inode *inode);
>> -extern void ext4_write_inline_data(struct inode *inode,
>> -                                struct ext4_iloc *iloc,
>> -                                void *buffer, loff_t pos,
>> -                                unsigned int len);
>> -extern int ext4_prepare_inline_data(handle_t *handle, struct inode *inode,
>> -                                 unsigned int len);
>> -extern int ext4_init_inline_data(handle_t *handle, struct inode *inode,
>> -                              unsigned int len);
>> -extern int ext4_destroy_inline_data(handle_t *handle, struct inode *inode);
>> -
>> -extern int ext4_readpage_inline(struct inode *inode, struct page *page);
>> -extern int ext4_try_to_write_inline_data(struct address_space *mapping,
>> -                                      struct inode *inode,
>> -                                      loff_t pos, unsigned len,
>> -                                      unsigned flags,
>> -                                      struct page **pagep);
>> -extern int ext4_write_inline_data_end(struct inode *inode,
>> -                                   loff_t pos, unsigned len,
>> -                                   unsigned copied,
>> -                                   struct page *page);
>> -extern struct buffer_head *
>> -ext4_journalled_write_inline_data(struct inode *inode,
>> -                               unsigned len,
>> -                               struct page *page);
>> -extern int ext4_da_write_inline_data_begin(struct address_space *mapping,
>> -                                        struct inode *inode,
>> -                                        loff_t pos, unsigned len,
>> -                                        unsigned flags,
>> -                                        struct page **pagep,
>> -                                        void **fsdata);
>> -extern int ext4_da_write_inline_data_end(struct inode *inode, loff_t pos,
>> -                                      unsigned len, unsigned copied,
>> -                                      struct page *page);
>> -extern int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
>> -                                  struct inode *inode);
>> -extern int ext4_try_create_inline_dir(handle_t *handle,
>> -                                   struct inode *parent,
>> -                                   struct inode *inode);
>> -extern int ext4_read_inline_dir(struct file *filp,
>> -                             void *dirent, filldir_t filldir,
>> -                             int *has_inline_data);
>> -extern struct buffer_head *ext4_find_inline_entry(struct inode *dir,
>> -                                     const struct qstr *d_name,
>> -                                     struct ext4_dir_entry_2 **res_dir,
>> -                                     int *has_inline_data);
>> -extern int ext4_delete_inline_entry(handle_t *handle,
>> -                                 struct inode *dir,
>> -                                 struct ext4_dir_entry_2 *de_del,
>> -                                 struct buffer_head *bh,
>> -                                 int *has_inline_data);
>> -extern int empty_inline_dir(struct inode *dir, int *has_inline_data);
>> -extern struct buffer_head *ext4_get_first_inline_block(struct inode *inode,
>> -                                     struct ext4_dir_entry_2 **parent_de,
>> -                                     int *retval);
>> -extern int ext4_inline_data_fiemap(struct inode *inode,
>> -                                struct fiemap_extent_info *fieinfo,
>> -                                int *has_inline);
>> -extern int ext4_try_to_evict_inline_data(handle_t *handle,
>> -                                      struct inode *inode,
>> -                                      int needed);
>> -extern void ext4_inline_data_truncate(struct inode *inode, int *has_inline);
>> -
>> -extern int ext4_convert_inline_data(struct inode *inode);
>> -
>>  #ifdef CONFIG_EXT4_FS_SECURITY
>>  extern int ext4_init_security(handle_t *handle, struct inode *inode,
>>                             struct inode *dir, const struct qstr *qstr);
>>
>
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