[2/5] ext4 : Update low level ext4 journal routines to specify gfp_mask for transaction allocation.

Update low level ext4 journal routines to pass an extra parameter
to journal allocation routines to specify whether transaction allocation
can fail or not. With this patch ext4_journal_start() can fail due to
ENOMEM. Added a new interface ext4_journal_start_tryhard() which isn't
supposed to fail and keep retrying till the allocation succeeds.


Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
---
 fs/ext4/ext4_jbd2.h |    8 +++++++-
 fs/ext4/super.c     |   15 +++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

 /*

On Sun 24-04-11 17:13:18, Manish Katiyar wrote:
> Update low level ext4 journal routines to pass an extra parameter
> to journal allocation routines to specify whether transaction allocation
> can fail or not. With this patch ext4_journal_start() can fail due to
> ENOMEM. Added a new interface ext4_journal_start_tryhard() which isn't
> supposed to fail and keep retrying till the allocation succeeds.
  As I wrote in a comment in the comment to the first patch, first just
make ext4_journal_start_sb() and similar functions pass false as a part of
the first patch.

Then it would be better to create a new function that passes true - the
name does not really matter since it will be removed later in the series
but it will help the review process. You can call it
ext4_journal_start_sb_enomem() or whatever. This way we keep backward
compatibility because currently all call sites really expect the retry
behavior. Then in the patch you can switch safe call sites to use _enomem
variant and at the end of the series as a separate patch you just do
renaming - ext4_journal_start_sb() becomes ext4_journal_start_sb_tryhard()
and ext4_journal_start_sb_enomem() becomes ext4_journal_start_sb().

								Honza

> Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
> ---
>  fs/ext4/ext4_jbd2.h |    8 +++++++-
>  fs/ext4/super.c     |   15 +++++++++++++--
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
> index d0f5353..ee6385c 100644
> --- a/fs/ext4/ext4_jbd2.h
> +++ b/fs/ext4/ext4_jbd2.h
> @@ -162,6 +162,7 @@ int __ext4_handle_dirty_super(const char *where,
> unsigned int line,
>  	__ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
> 
>  handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
> +handle_t *ext4_journal_start_sb_tryhard(struct super_block *sb, int nblocks);
>  int __ext4_journal_stop(const char *where, unsigned int line,
> handle_t *handle);
> 
>  #define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
> @@ -207,6 +208,11 @@ static inline handle_t *ext4_journal_start(struct
> inode *inode, int nblocks)
>  	return ext4_journal_start_sb(inode->i_sb, nblocks);
>  }
> 
> +static inline handle_t *ext4_journal_start_tryhard(struct inode
> *inode, int nblocks)
> +{
> +	return ext4_journal_start_sb_tryhard(inode->i_sb, nblocks);
> +}
> +
>  #define ext4_journal_stop(handle) \
>  	__ext4_journal_stop(__func__, __LINE__, (handle))
> 
> @@ -225,7 +231,7 @@ static inline int ext4_journal_extend(handle_t
> *handle, int nblocks)
>  static inline int ext4_journal_restart(handle_t *handle, int nblocks)
>  {
>  	if (ext4_handle_valid(handle))
> -		return jbd2_journal_restart(handle, nblocks);
> +		return jbd2_journal_restart(handle, nblocks, false);
>  	return 0;
>  }
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 8553dfb..03eac6a 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -247,7 +247,8 @@ static void ext4_put_nojournal(handle_t *handle)
>   * ext4 prevents a new handle from being started by s_frozen, which
>   * is in an upper layer.
>   */
> -handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
> +static handle_t *__ext4_journal_start_sb(struct super_block *sb,
> +					 int nblocks, bool errok)
>  {
>  	journal_t *journal;
>  	handle_t  *handle;
> @@ -279,7 +280,17 @@ handle_t *ext4_journal_start_sb(struct
> super_block *sb, int nblocks)
>  		ext4_abort(sb, "Detected aborted journal");
>  		return ERR_PTR(-EROFS);
>  	}
> -	return jbd2_journal_start(journal, nblocks);
> +	return jbd2_journal_start(journal, nblocks, errok);
> +}
> +
> +handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
> +{
> +	return __ext4_journal_start_sb(sb, nblocks, true);
> +}
> +
> +handle_t *ext4_journal_start_sb_tryhard(struct super_block *sb, int nblocks)
> +{
> +	return __ext4_journal_start_sb(sb, nblocks, false);
>  }
> 
>  /*
> -- 
> 1.7.1
> 
> -- 
> Thanks -
> Manish

> From 365d29cd8d5b139e332965a536dd380e656bbd15 Mon Sep 17 00:00:00 2001
> From: Manish Katiyar <mkatiyar@gmail.com>
> Date: Sun, 24 Apr 2011 16:49:48 -0700
> Subject: [PATCH 2/5] Update low level ext4 journal routines to pass an extra paramter
>  to journal allocation routines to specify whether transaction allocation
>  can fail or not. With this patch ext4_journal_start() can fail due to
>  ENOMEM. Added a new interface ext4_journal_start_tryhard() which isn't
>  supposed to fail and keep retrying till the allocation succeeds.
> 
> 
> Signed-off-by: Manish Katiyar <mkatiyar@gmail.com>
> ---
>  fs/ext4/ext4_jbd2.h |    8 +++++++-
>  fs/ext4/super.c     |   15 +++++++++++++--
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
> index d0f5353..ee6385c 100644
> --- a/fs/ext4/ext4_jbd2.h
> +++ b/fs/ext4/ext4_jbd2.h
> @@ -162,6 +162,7 @@ int __ext4_handle_dirty_super(const char *where, unsigned int line,
>  	__ext4_handle_dirty_super(__func__, __LINE__, (handle), (sb))
>  
>  handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks);
> +handle_t *ext4_journal_start_sb_tryhard(struct super_block *sb, int nblocks);
>  int __ext4_journal_stop(const char *where, unsigned int line, handle_t *handle);
>  
>  #define EXT4_NOJOURNAL_MAX_REF_COUNT ((unsigned long) 4096)
> @@ -207,6 +208,11 @@ static inline handle_t *ext4_journal_start(struct inode *inode, int nblocks)
>  	return ext4_journal_start_sb(inode->i_sb, nblocks);
>  }
>  
> +static inline handle_t *ext4_journal_start_tryhard(struct inode *inode, int nblocks)
> +{
> +	return ext4_journal_start_sb_tryhard(inode->i_sb, nblocks);
> +}
> +
>  #define ext4_journal_stop(handle) \
>  	__ext4_journal_stop(__func__, __LINE__, (handle))
>  
> @@ -225,7 +231,7 @@ static inline int ext4_journal_extend(handle_t *handle, int nblocks)
>  static inline int ext4_journal_restart(handle_t *handle, int nblocks)
>  {
>  	if (ext4_handle_valid(handle))
> -		return jbd2_journal_restart(handle, nblocks);
> +		return jbd2_journal_restart(handle, nblocks, false);
>  	return 0;
>  }
>  
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 8553dfb..03eac6a 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -247,7 +247,8 @@ static void ext4_put_nojournal(handle_t *handle)
>   * ext4 prevents a new handle from being started by s_frozen, which
>   * is in an upper layer.
>   */
> -handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
> +static handle_t *__ext4_journal_start_sb(struct super_block *sb,
> +					 int nblocks, bool errok)
>  {
>  	journal_t *journal;
>  	handle_t  *handle;
> @@ -279,7 +280,17 @@ handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
>  		ext4_abort(sb, "Detected aborted journal");
>  		return ERR_PTR(-EROFS);
>  	}
> -	return jbd2_journal_start(journal, nblocks);
> +	return jbd2_journal_start(journal, nblocks, errok);
> +}
> + 
> +handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
> +{
> +	return __ext4_journal_start_sb(sb, nblocks, true);
> +}
> +
> +handle_t *ext4_journal_start_sb_tryhard(struct super_block *sb, int nblocks)
> +{
> +	return __ext4_journal_start_sb(sb, nblocks, false);
>  }
>  
>  /*
> -- 
> 1.7.1
>