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Re: [PATCH 2/2] Add support to RENAME_EXCHANGE flag V8

To: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Subject: Re: [PATCH 2/2] Add support to RENAME_EXCHANGE flag V8
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 28 Nov 2014 12:38:30 +1100
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1416923368-28322-3-git-send-email-cmaiolino@xxxxxxxxxx>
References: <1416923368-28322-1-git-send-email-cmaiolino@xxxxxxxxxx> <1416923368-28322-3-git-send-email-cmaiolino@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Nov 25, 2014 at 11:49:28AM -0200, Carlos Maiolino wrote:
> Adds a new function named xfs_cross_rename(), responsible to handle requests
> from sys_renameat2() using RENAME_EXCHANGE flag.
> 
> Changelog:
> 
>       V2: - refactor xfs_cross_rename() to not duplicate code from 
> xfs_rename()
> 
>       V3: - fix indentation to avoid 80 column crossing, decrease the amount 
> of
>             arguments passed to xfs_cross_rename()
>           - Rebase patches over the latest linux code
> 
>       v4: - use a label/goto statement instead of an if conditional after
>             xfs_cross_rename() return, to finish the rename operation
>           - Make xfs_cross_rename() static
>           - Fix some comments
> 
>       V5: - Keep all the code under 80 columns
> 
>       V6: - Ensure i_mode of both files are updated during exchange
> 
>       V7: - Use struct names instead of typedefs in the xfs_cross_rename()
>             definition
> 
>       V8: - Replace src/target names for better variable names
>           - Log and timestamp updates done in different places
>           - Fix missing space in comments
>           - get rid of {src,tgt}_is_directory and new_parent variables

FYI, Changelog should be in the cover patch 0, not in the commit
message for the individual patch.

> Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
>  fs/xfs/xfs_inode.c | 112 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/xfs/xfs_inode.h |   2 +-
>  fs/xfs/xfs_iops.c  |  15 +++++--
>  3 files changed, 123 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 8ed049d..5c5ed99 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -2668,6 +2668,102 @@ xfs_sort_for_rename(
>       }
>  }
>  
> +/* xfs_cross_rename()
> + *
> + * responsible to handle RENAME_EXCHANGE flag
> + * in renameat2() sytemcall

Comments can use all 80 columns. And the first line of the comment
is "/*" by itself.

> + */
> +STATIC int
> +xfs_cross_rename(
> +     struct xfs_trans        *tp,
> +     struct xfs_inode        *dp1,
> +     struct xfs_name         *name1,
> +     struct xfs_inode        *ip1,
> +     struct xfs_inode        *dp2,
> +     struct xfs_name         *name2,
> +     struct xfs_inode        *ip2,
> +     struct xfs_bmap_free    *free_list,
> +     xfs_fsblock_t           *first_block,
> +     int                     spaceres)
> +{
> +     int             error = 0;
> +
> +     /* Replace source inode */

still got source/target in comments that don't make sense. "Swap
inode number for dirent in first parent" might be better...

> +     error = xfs_dir_replace(tp, dp1, name1,
> +                             ip2->i_ino,
> +                             first_block, free_list, spaceres);
> +     if (error)
> +             goto out;
> +
> +     /* Replace target inode */

        /* Swap inode number for dirent in second parent */

> +     error = xfs_dir_replace(tp, dp2, name2,
> +                             ip1->i_ino,
> +                             first_block, free_list, spaceres);
> +     if (error)
> +             goto out;
> +     /*
> +      * If we're renaming one or more directories across different parents,
> +      * update the respective ".." entries (and link counts) to match the new
> +      * parents.
> +      */
> +     if (dp1 != dp2) {
> +
> +             if (S_ISDIR(ip2->i_d.di_mode)) {
> +                     error = xfs_dir_replace(tp, ip2, &xfs_name_dotdot,
> +                                             dp1->i_ino, first_block,
> +                                             free_list, spaceres);
> +                     if (error)
> +                             goto out;

now ip2 is modified, so it ctime/mtime dirty.

> +
> +                     /* transfer target ".." reference to dp1 */
> +                     if (!S_ISDIR(ip1->i_d.di_mode)) {
> +                             error = xfs_droplink(tp, dp2);
> +                             if (error)
> +                                     goto out;
> +                             error = xfs_bumplink(tp, dp1);
> +                             if (error)
> +                                     goto out;
> +                     }
> +                     xfs_trans_ichgtime(tp, ip1, XFS_ICHGTIME_CHG);
> +                     xfs_trans_ichgtime(tp, ip2,
> +                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
> +                     xfs_trans_log_inode(tp, ip2, XFS_ILOG_CORE);

But now you're unconditionally changing ctime on ip1 without it
having been modified and you aren't logging the change. Why is the
ctime changing (comments, please!)?


> +             }
> +
> +             if (S_ISDIR(ip1->i_d.di_mode)) {
> +                     error = xfs_dir_replace(tp, ip1, &xfs_name_dotdot,
> +                                             dp2->i_ino, first_block,
> +                                             free_list, spaceres);
> +                     if (error)
> +                             goto out;

here ip2 is modified

> +
> +                     /* transfer src ".." reference to dp2 */
> +                     if (!S_ISDIR(ip2->i_d.di_mode)) {
> +                             error = xfs_droplink(tp, dp1);
> +                             if (error)
> +                                     goto out;
> +                             error = xfs_bumplink(tp, dp2);
> +                             if (error)
> +                                     goto out;
> +                     }
> +                     xfs_trans_ichgtime(tp, ip1,
> +                                        XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
> +                     xfs_trans_ichgtime(tp, ip2, XFS_ICHGTIME_CHG);
> +                     xfs_trans_log_inode(tp, ip1, XFS_ILOG_CORE);

and same again - changing ctime on ip2 without logging it.

> +             }
> +             xfs_trans_ichgtime(tp, dp2,
> +                                XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
> +             xfs_trans_log_inode(tp, dp2, XFS_ILOG_CORE);
> +     }
> +     xfs_trans_ichgtime(tp, dp1, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
> +     xfs_trans_log_inode(tp, dp1, XFS_ILOG_CORE);

perhaps:

        int     ip1_flags = 0;
        int     ip2_flags = 0;
        int     dp2_flags = 0;

        if (dp1 != dp2)
                dp2_flags = XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;

                if (S_ISDIR(ip1)) {
                        ip1_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                        ip2_flags |= XFS_ICHGTIME_CHG; /* because ... */
                        .....
                }

                if (S_ISDIR(ip2)) {
                        ip1_flags |= XFS_ICHGTIME_CHG; /* because ... */
                        ip2_flags |= XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG;
                        .....
                }
        }

        if (ip1_flags) {
                xfs_trans_ichgtime(tp, ip1, ip1_flags);
                xfs_trans_log_inode(tp, ip1);
        }
        if (ip2_flags) {
                xfs_trans_ichgtime(tp, ip2, ip2_flags);
                xfs_trans_log_inode(tp, ip2);
        }
        if (dp2_flags) {
                xfs_trans_ichgtime(tp, dp2, ip2_flags);
                xfs_trans_log_inode(tp, dp2);
        }
        xfs_trans_ichgtime(tp, dp2, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
        xfs_trans_log_inode(tp, dp2);
> +
> +out:
> +     return error;
> +}
> +
>  /*
>   * xfs_rename
>   */
> @@ -2678,7 +2774,8 @@ xfs_rename(
>       xfs_inode_t     *src_ip,
>       xfs_inode_t     *target_dp,
>       struct xfs_name *target_name,
> -     xfs_inode_t     *target_ip)
> +     xfs_inode_t     *target_ip,
> +     unsigned int    flags)
>  {
>       xfs_trans_t     *tp = NULL;
>       xfs_mount_t     *mp = src_dp->i_mount;
> @@ -2706,6 +2803,7 @@ xfs_rename(
>       cancel_flags = XFS_TRANS_RELEASE_LOG_RES;
>       spaceres = XFS_RENAME_SPACE_RES(mp, target_name->len);
>       error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, spaceres, 0);
> +
>       if (error == -ENOSPC) {

Stray new line.

>               spaceres = 0;
>               error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, 0, 0);
> @@ -2756,6 +2854,17 @@ xfs_rename(
>       }
>  
>       /*
> +      * Handle RENAME_EXCHANGE flags
> +     */

Comment whitespace still needs fixing.

> +     if (flags & RENAME_EXCHANGE) {
> +             error = xfs_cross_rename(tp, src_dp, src_name, src_ip,
> +                                      target_dp, target_name, target_ip,
> +                                      &free_list, &first_block, spaceres);
> +             if (error)
> +                     goto abort_return;
> +             goto finish_rename;
> +     }
> +     /*
>        * Set up the target.
>        */

Put an empty line between the "}" and the start of the comment.

>       if (target_ip == NULL) {
> @@ -2894,6 +3003,7 @@ xfs_rename(
>       if (new_parent)
>               xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
>  
> +finish_rename:
>       /*
>        * If this is a synchronous mount, make sure that the
>        * rename transaction goes to disk before returning to
> diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> index 9af2882..051d9f0 100644
> --- a/fs/xfs/xfs_inode.h
> +++ b/fs/xfs/xfs_inode.h
> @@ -340,7 +340,7 @@ int               xfs_link(struct xfs_inode *tdp, struct 
> xfs_inode *sip,
>  int          xfs_rename(struct xfs_inode *src_dp, struct xfs_name *src_name,
>                          struct xfs_inode *src_ip, struct xfs_inode 
> *target_dp,
>                          struct xfs_name *target_name,
> -                        struct xfs_inode *target_ip);
> +                        struct xfs_inode *target_ip, unsigned int flags);
>  
>  void         xfs_ilock(xfs_inode_t *, uint);
>  int          xfs_ilock_nowait(xfs_inode_t *, uint);
> diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> index 0b8704c..4e5d8ce 100644
> --- a/fs/xfs/xfs_iops.c
> +++ b/fs/xfs/xfs_iops.c
> @@ -387,19 +387,26 @@ xfs_vn_rename(
>       unsigned int    flags)
>  {
>       struct inode    *new_inode = ndentry->d_inode;
> +     int             omode = 0;
>       struct xfs_name oname;
>       struct xfs_name nname;
>  
> -     /* XFS does not support RENAME_EXCHANGE yet */
> -     if (flags & ~RENAME_NOREPLACE)
> +     if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
>               return -EINVAL;
>  
> -     xfs_dentry_to_name(&oname, odentry, 0);
> +     /*
> +      * if we are exchanging files, we should set
> +      * i_mode of both files
> +      */

Comments can use all 80 characters of the line. Also, s/should/need
to/.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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