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

To: xfs@xxxxxxxxxxx
Subject: [PATCH 2/2] Add support to RENAME_EXCHANGE flag V8
From: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
Date: Tue, 25 Nov 2014 11:49:28 -0200
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1416923368-28322-1-git-send-email-cmaiolino@xxxxxxxxxx>
References: <1416923368-28322-1-git-send-email-cmaiolino@xxxxxxxxxx>
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

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
+ */
+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 */
+       error = xfs_dir_replace(tp, dp1, name1,
+                               ip2->i_ino,
+                               first_block, free_list, spaceres);
+       if (error)
+               goto out;
+
+       /* Replace target inode */
+       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;
+
+                       /* 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);
+               }
+
+               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;
+
+                       /* 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);
+               }
+               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);
+
+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) {
                spaceres = 0;
                error = xfs_trans_reserve(tp, &M_RES(mp)->tr_rename, 0, 0);
@@ -2756,6 +2854,17 @@ xfs_rename(
        }
 
        /*
+        * Handle RENAME_EXCHANGE flags
+       */
+       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.
         */
        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
+        */
+       if (flags & RENAME_EXCHANGE)
+               omode = ndentry->d_inode->i_mode;
+
+       xfs_dentry_to_name(&oname, odentry, omode);
        xfs_dentry_to_name(&nname, ndentry, odentry->d_inode->i_mode);
 
        return xfs_rename(XFS_I(odir), &oname, XFS_I(odentry->d_inode),
                          XFS_I(ndir), &nname,
-                         new_inode ? XFS_I(new_inode) : NULL);
+                         new_inode ? XFS_I(new_inode) : NULL, flags);
 }
 
 /*
-- 
2.1.0

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