xfs: create libxfs helper to rename two directory entries

Create a new libxfs function to rename two directory entries.  The
upcoming metadata directory feature will need this to replace a metadata
inode directory entry.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

3 files changed, 257 insertions, 206 deletions

diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index efda14d903e3..779df16d2841 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -22,6 +22,7 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_trans_space.h"
 #include "xfs_ag.h"
+#include "xfs_ialloc.h"
 
 struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR };
 
@@ -1024,3 +1025,246 @@ xfs_dir_exchange(
 
 	return 0;
 }
+
+/*
+ * Given an entry (@src_name, @src_ip) in directory @src_dp, make the entry
+ * @target_name in directory @target_dp point to @src_ip and remove the
+ * original entry, cleaning up everything left behind.
+ *
+ * Cleanup involves dropping a link count on @target_ip, and either removing
+ * the (@src_name, @src_ip) entry from @src_dp or simply replacing the entry
+ * with (@src_name, @wip) if a whiteout inode @wip is supplied.
+ *
+ * All inodes must have the ILOCK held.  We assume that if @src_ip is a
+ * directory then its '..' doesn't already point to @target_dp, and that @wip
+ * is a freshly allocated whiteout.
+ */
+int
+xfs_dir_rename(
+	struct xfs_trans	*tp,
+	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,
+	unsigned int		spaceres,
+	struct xfs_inode	*wip)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	bool			new_parent = (src_dp != target_dp);
+	bool			src_is_directory;
+	int			error;
+
+	src_is_directory = S_ISDIR(VFS_I(src_ip)->i_mode);
+
+	/*
+	 * Check for expected errors before we dirty the transaction
+	 * so we can return an error without a transaction abort.
+	 *
+	 * Extent count overflow check:
+	 *
+	 * From the perspective of src_dp, a rename operation is essentially a
+	 * directory entry remove operation. Hence the only place where we check
+	 * for extent count overflow for src_dp is in
+	 * xfs_bmap_del_extent_real(). xfs_bmap_del_extent_real() returns
+	 * -ENOSPC when it detects a possible extent count overflow and in
+	 * response, the higher layers of directory handling code do the
+	 * following:
+	 * 1. Data/Free blocks: XFS lets these blocks linger until a
+	 *    future remove operation removes them.
+	 * 2. Dabtree blocks: XFS swaps the blocks with the last block in the
+	 *    Leaf space and unmaps the last block.
+	 *
+	 * For target_dp, there are two cases depending on whether the
+	 * destination directory entry exists or not.
+	 *
+	 * When destination directory entry does not exist (i.e. target_ip ==
+	 * NULL), extent count overflow check is performed only when transaction
+	 * has a non-zero sized space reservation associated with it.  With a
+	 * zero-sized space reservation, XFS allows a rename operation to
+	 * continue only when the directory has sufficient free space in its
+	 * data/leaf/free space blocks to hold the new entry.
+	 *
+	 * When destination directory entry exists (i.e. target_ip != NULL), all
+	 * we need to do is change the inode number associated with the already
+	 * existing entry. Hence there is no need to perform an extent count
+	 * overflow check.
+	 */
+	if (target_ip == NULL) {
+		/*
+		 * If there's no space reservation, check the entry will
+		 * fit before actually inserting it.
+		 */
+		if (!spaceres) {
+			error = xfs_dir_canenter(tp, target_dp, target_name);
+			if (error)
+				return error;
+		} else {
+			error = xfs_iext_count_may_overflow(target_dp,
+					XFS_DATA_FORK,
+					XFS_IEXT_DIR_MANIP_CNT(mp));
+			if (error)
+				return error;
+		}
+	} else {
+		/*
+		 * If target exists and it's a directory, check that whether
+		 * it can be destroyed.
+		 */
+		if (S_ISDIR(VFS_I(target_ip)->i_mode) &&
+		    (!xfs_dir_isempty(target_ip) ||
+		     (VFS_I(target_ip)->i_nlink > 2)))
+			return -EEXIST;
+	}
+
+	/*
+	 * Directory entry creation below may acquire the AGF. Remove
+	 * the whiteout from the unlinked list first to preserve correct
+	 * AGI/AGF locking order. This dirties the transaction so failures
+	 * after this point will abort and log recovery will clean up the
+	 * mess.
+	 *
+	 * For whiteouts, we need to bump the link count on the whiteout
+	 * inode. After this point, we have a real link, clear the tmpfile
+	 * state flag from the inode so it doesn't accidentally get misused
+	 * in future.
+	 */
+	if (wip) {
+		struct xfs_perag	*pag;
+
+		ASSERT(VFS_I(wip)->i_nlink == 0);
+
+		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, wip->i_ino));
+		error = xfs_iunlink_remove(tp, pag, wip);
+		xfs_perag_put(pag);
+		if (error)
+			return error;
+
+		xfs_bumplink(tp, wip);
+	}
+
+	/*
+	 * Set up the target.
+	 */
+	if (target_ip == NULL) {
+		/*
+		 * If target does not exist and the rename crosses
+		 * directories, adjust the target directory link count
+		 * to account for the ".." reference from the new entry.
+		 */
+		error = xfs_dir_createname(tp, target_dp, target_name,
+					   src_ip->i_ino, spaceres);
+		if (error)
+			return error;
+
+		xfs_trans_ichgtime(tp, target_dp,
+					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+
+		if (new_parent && src_is_directory) {
+			xfs_bumplink(tp, target_dp);
+		}
+	} else { /* target_ip != NULL */
+		/*
+		 * Link the source inode under the target name.
+		 * If the source inode is a directory and we are moving
+		 * it across directories, its ".." entry will be
+		 * inconsistent until we replace that down below.
+		 *
+		 * In case there is already an entry with the same
+		 * name at the destination directory, remove it first.
+		 */
+		error = xfs_dir_replace(tp, target_dp, target_name,
+					src_ip->i_ino, spaceres);
+		if (error)
+			return error;
+
+		xfs_trans_ichgtime(tp, target_dp,
+					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+
+		/*
+		 * Decrement the link count on the target since the target
+		 * dir no longer points to it.
+		 */
+		error = xfs_droplink(tp, target_ip);
+		if (error)
+			return error;
+
+		if (src_is_directory) {
+			/*
+			 * Drop the link from the old "." entry.
+			 */
+			error = xfs_droplink(tp, target_ip);
+			if (error)
+				return error;
+		}
+	} /* target_ip != NULL */
+
+	/*
+	 * Remove the source.
+	 */
+	if (new_parent && src_is_directory) {
+		/*
+		 * Rewrite the ".." entry to point to the new
+		 * directory.
+		 */
+		error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
+					target_dp->i_ino, spaceres);
+		ASSERT(error != -EEXIST);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * We always want to hit the ctime on the source inode.
+	 *
+	 * This isn't strictly required by the standards since the source
+	 * inode isn't really being changed, but old unix file systems did
+	 * it and some incremental backup programs won't work without it.
+	 */
+	xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
+	xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);
+
+	/*
+	 * Adjust the link count on src_dp.  This is necessary when
+	 * renaming a directory, either within one parent when
+	 * the target existed, or across two parent directories.
+	 */
+	if (src_is_directory && (new_parent || target_ip != NULL)) {
+
+		/*
+		 * Decrement link count on src_directory since the
+		 * entry that's moved no longer points to it.
+		 */
+		error = xfs_droplink(tp, src_dp);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * For whiteouts, we only need to update the source dirent with the
+	 * inode number of the whiteout inode rather than removing it
+	 * altogether.
+	 */
+	if (wip) {
+		error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino,
+					spaceres);
+	} else {
+		/*
+		 * NOTE: We don't need to check for extent count overflow here
+		 * because the dir remove name code will leave the dir block in
+		 * place if the extent count would overflow.
+		 */
+		error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
+					   spaceres);
+	}
+	if (error)
+		return error;
+
+	xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
+	xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
+	if (new_parent)
+		xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
+
+	return 0;
+}
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index bbe022e6e89f..62e53816e292 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -261,5 +261,10 @@ int xfs_dir_exchange(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, unsigned int spaceres);
+int xfs_dir_rename(struct xfs_trans *tp, 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, unsigned int spaceres,
+		struct xfs_inode *wip);
 
 #endif	/* __XFS_DIR2_H__ */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index b2cbf084b95d..5ab251c8a5dd 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2363,68 +2363,6 @@ xfs_rename(
 					spaceres);
 
 	/*
-	 * Check for expected errors before we dirty the transaction
-	 * so we can return an error without a transaction abort.
-	 *
-	 * Extent count overflow check:
-	 *
-	 * From the perspective of src_dp, a rename operation is essentially a
-	 * directory entry remove operation. Hence the only place where we check
-	 * for extent count overflow for src_dp is in
-	 * xfs_bmap_del_extent_real(). xfs_bmap_del_extent_real() returns
-	 * -ENOSPC when it detects a possible extent count overflow and in
-	 * response, the higher layers of directory handling code do the
-	 * following:
-	 * 1. Data/Free blocks: XFS lets these blocks linger until a
-	 *    future remove operation removes them.
-	 * 2. Dabtree blocks: XFS swaps the blocks with the last block in the
-	 *    Leaf space and unmaps the last block.
-	 *
-	 * For target_dp, there are two cases depending on whether the
-	 * destination directory entry exists or not.
-	 *
-	 * When destination directory entry does not exist (i.e. target_ip ==
-	 * NULL), extent count overflow check is performed only when transaction
-	 * has a non-zero sized space reservation associated with it.  With a
-	 * zero-sized space reservation, XFS allows a rename operation to
-	 * continue only when the directory has sufficient free space in its
-	 * data/leaf/free space blocks to hold the new entry.
-	 *
-	 * When destination directory entry exists (i.e. target_ip != NULL), all
-	 * we need to do is change the inode number associated with the already
-	 * existing entry. Hence there is no need to perform an extent count
-	 * overflow check.
-	 */
-	if (target_ip == NULL) {
-		/*
-		 * If there's no space reservation, check the entry will
-		 * fit before actually inserting it.
-		 */
-		if (!spaceres) {
-			error = xfs_dir_canenter(tp, target_dp, target_name);
-			if (error)
-				goto out_trans_cancel;
-		} else {
-			error = xfs_iext_count_may_overflow(target_dp,
-					XFS_DATA_FORK,
-					XFS_IEXT_DIR_MANIP_CNT(mp));
-			if (error)
-				goto out_trans_cancel;
-		}
-	} else {
-		/*
-		 * If target exists and it's a directory, check that whether
-		 * it can be destroyed.
-		 */
-		if (S_ISDIR(VFS_I(target_ip)->i_mode) &&
-		    (!xfs_dir_isempty(target_ip) ||
-		     (VFS_I(target_ip)->i_nlink > 2))) {
-			error = -EEXIST;
-			goto out_trans_cancel;
-		}
-	}
-
-	/*
 	 * Lock the AGI buffers we need to handle bumping the nlink of the
 	 * whiteout inode off the unlinked list and to handle dropping the
 	 * nlink of the target inode.  Per locking order rules, do this in
@@ -2448,156 +2386,20 @@ xfs_rename(
 		}
 	}
 
-	/*
-	 * Directory entry creation below may acquire the AGF. Remove
-	 * the whiteout from the unlinked list first to preserve correct
-	 * AGI/AGF locking order. This dirties the transaction so failures
-	 * after this point will abort and log recovery will clean up the
-	 * mess.
-	 *
-	 * For whiteouts, we need to bump the link count on the whiteout
-	 * inode. After this point, we have a real link, clear the tmpfile
-	 * state flag from the inode so it doesn't accidentally get misused
-	 * in future.
-	 */
-	if (wip) {
-		struct xfs_perag	*pag;
-
-		ASSERT(VFS_I(wip)->i_nlink == 0);
-
-		pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, wip->i_ino));
-		error = xfs_iunlink_remove(tp, pag, wip);
-		xfs_perag_put(pag);
-		if (error)
-			goto out_trans_cancel;
-
-		xfs_bumplink(tp, wip);
-		VFS_I(wip)->i_state &= ~I_LINKABLE;
-	}
-
-	/*
-	 * Set up the target.
-	 */
-	if (target_ip == NULL) {
-		/*
-		 * If target does not exist and the rename crosses
-		 * directories, adjust the target directory link count
-		 * to account for the ".." reference from the new entry.
-		 */
-		error = xfs_dir_createname(tp, target_dp, target_name,
-					   src_ip->i_ino, spaceres);
-		if (error)
-			goto out_trans_cancel;
-
-		xfs_trans_ichgtime(tp, target_dp,
-					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
-
-		if (new_parent && src_is_directory) {
-			xfs_bumplink(tp, target_dp);
-		}
-	} else { /* target_ip != NULL */
-		/*
-		 * Link the source inode under the target name.
-		 * If the source inode is a directory and we are moving
-		 * it across directories, its ".." entry will be
-		 * inconsistent until we replace that down below.
-		 *
-		 * In case there is already an entry with the same
-		 * name at the destination directory, remove it first.
-		 */
-		error = xfs_dir_replace(tp, target_dp, target_name,
-					src_ip->i_ino, spaceres);
-		if (error)
-			goto out_trans_cancel;
-
-		xfs_trans_ichgtime(tp, target_dp,
-					XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
-
-		/*
-		 * Decrement the link count on the target since the target
-		 * dir no longer points to it.
-		 */
-		error = xfs_droplink(tp, target_ip);
-		if (error)
-			goto out_trans_cancel;
-
-		if (src_is_directory) {
-			/*
-			 * Drop the link from the old "." entry.
-			 */
-			error = xfs_droplink(tp, target_ip);
-			if (error)
-				goto out_trans_cancel;
-		}
-	} /* target_ip != NULL */
-
-	/*
-	 * Remove the source.
-	 */
-	if (new_parent && src_is_directory) {
-		/*
-		 * Rewrite the ".." entry to point to the new
-		 * directory.
-		 */
-		error = xfs_dir_replace(tp, src_ip, &xfs_name_dotdot,
-					target_dp->i_ino, spaceres);
-		ASSERT(error != -EEXIST);
-		if (error)
-			goto out_trans_cancel;
-	}
-
-	/*
-	 * We always want to hit the ctime on the source inode.
-	 *
-	 * This isn't strictly required by the standards since the source
-	 * inode isn't really being changed, but old unix file systems did
-	 * it and some incremental backup programs won't work without it.
-	 */
-	xfs_trans_ichgtime(tp, src_ip, XFS_ICHGTIME_CHG);
-	xfs_trans_log_inode(tp, src_ip, XFS_ILOG_CORE);
-
-	/*
-	 * Adjust the link count on src_dp.  This is necessary when
-	 * renaming a directory, either within one parent when
-	 * the target existed, or across two parent directories.
-	 */
-	if (src_is_directory && (new_parent || target_ip != NULL)) {
-
-		/*
-		 * Decrement link count on src_directory since the
-		 * entry that's moved no longer points to it.
-		 */
-		error = xfs_droplink(tp, src_dp);
-		if (error)
-			goto out_trans_cancel;
-	}
+	error = xfs_dir_rename(tp, src_dp, src_name, src_ip, target_dp,
+			target_name, target_ip, spaceres, wip);
+	if (error)
+		goto out_trans_cancel;
 
-	/*
-	 * For whiteouts, we only need to update the source dirent with the
-	 * inode number of the whiteout inode rather than removing it
-	 * altogether.
-	 */
 	if (wip) {
-		error = xfs_dir_replace(tp, src_dp, src_name, wip->i_ino,
-					spaceres);
-	} else {
 		/*
-		 * NOTE: We don't need to check for extent count overflow here
-		 * because the dir remove name code will leave the dir block in
-		 * place if the extent count would overflow.
+		 * Now we have a real link, clear the "I'm a tmpfile" state
+		 * flag from the inode so it doesn't accidentally get misused in
+		 * future.
 		 */
-		error = xfs_dir_removename(tp, src_dp, src_name, src_ip->i_ino,
-					   spaceres);
+		VFS_I(wip)->i_state &= ~I_LINKABLE;
 	}
 
-	if (error)
-		goto out_trans_cancel;
-
-	xfs_trans_ichgtime(tp, src_dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
-	xfs_trans_log_inode(tp, src_dp, XFS_ILOG_CORE);
-	if (new_parent)
-		xfs_trans_log_inode(tp, target_dp, XFS_ILOG_CORE);
-
 	error = xfs_finish_rename(tp);
 	if (wip)
 		xfs_irele(wip);