ocfs2: Add total entry count to dx_root_block

This little bit of extra accounting speeds up ocfs2_empty_dir()
dramatically by allowing us to short-circuit the full directory scan.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>

2 files changed, 124 insertions, 44 deletions

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 52df9125a79..5e6aeb00cb4 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -1322,16 +1322,15 @@ static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
          * entry yet. Likewise, successful return means we *must*
          * remove the indexed entry.
          *
-         * We're also careful to journal the root tree block here if
-         * we're going to be adding to the start of the free list.
+         * We're also careful to journal the root tree block here as
+         * the entry count needs to be updated. Also, we might be
+         * adding to the start of the free list.
          */
-        if (add_to_free_list || ocfs2_dx_root_inline(dx_root)) {
-                ret = ocfs2_journal_access_dr(handle, dir, dx_root_bh,
-                                              OCFS2_JOURNAL_ACCESS_WRITE);
-                if (ret) {
-                        mlog_errno(ret);
-                        goto out;
-                }
+        ret = ocfs2_journal_access_dr(handle, dir, dx_root_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
         }
 
         if (!ocfs2_dx_root_inline(dx_root)) {
@@ -1365,11 +1364,12 @@ static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
         /* leaf_bh was journal_accessed for us in __ocfs2_delete_entry */
         ocfs2_journal_dirty(handle, leaf_bh);
 
+        le32_add_cpu(&dx_root->dr_num_entries, -1);
+        ocfs2_journal_dirty(handle, dx_root_bh);
+
         ocfs2_dx_list_remove_entry(entry_list, index);
 
-        if (ocfs2_dx_root_inline(dx_root))
-                ocfs2_journal_dirty(handle, dx_root_bh);
-        else
+        if (!ocfs2_dx_root_inline(dx_root))
                 ocfs2_journal_dirty(handle, lookup->dl_dx_leaf_bh);
 
 out:
@@ -1508,13 +1508,20 @@ out:
         return ret;
 }
 
-static int ocfs2_dx_inline_root_insert(struct inode *dir, handle_t *handle,
-                                       struct ocfs2_dx_hinfo *hinfo,
-                                       u64 dirent_blk,
-                                       struct buffer_head *dx_root_bh)
+static void ocfs2_dx_inline_root_insert(struct inode *dir, handle_t *handle,
+                                        struct ocfs2_dx_hinfo *hinfo,
+                                        u64 dirent_blk,
+                                        struct ocfs2_dx_root_block *dx_root)
 {
-        int ret;
+        ocfs2_dx_entry_list_insert(&dx_root->dr_entries, hinfo, dirent_blk);
+}
+
+static int ocfs2_dx_dir_insert(struct inode *dir, handle_t *handle,
+                               struct ocfs2_dir_lookup_result *lookup)
+{
+        int ret = 0;
         struct ocfs2_dx_root_block *dx_root;
+        struct buffer_head *dx_root_bh = lookup->dl_dx_root_bh;
 
         ret = ocfs2_journal_access_dr(handle, dir, dx_root_bh,
                                       OCFS2_JOURNAL_ACCESS_WRITE);
@@ -1523,31 +1530,27 @@ static int ocfs2_dx_inline_root_insert(struct inode *dir, handle_t *handle,
                 goto out;
         }
 
-        dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
-        ocfs2_dx_entry_list_insert(&dx_root->dr_entries, hinfo, dirent_blk);
+        dx_root = (struct ocfs2_dx_root_block *)lookup->dl_dx_root_bh->b_data;
+        if (ocfs2_dx_root_inline(dx_root)) {
+                ocfs2_dx_inline_root_insert(dir, handle,
+                                            &lookup->dl_hinfo,
+                                            lookup->dl_leaf_bh->b_blocknr,
+                                            dx_root);
+        } else {
+                ret = __ocfs2_dx_dir_leaf_insert(dir, handle, &lookup->dl_hinfo,
+                                                 lookup->dl_leaf_bh->b_blocknr,
+                                                 lookup->dl_dx_leaf_bh);
+                if (ret)
+                        goto out;
+        }
+
+        le32_add_cpu(&dx_root->dr_num_entries, 1);
         ocfs2_journal_dirty(handle, dx_root_bh);
 
 out:
         return ret;
 }
 
-static int ocfs2_dx_dir_insert(struct inode *dir, handle_t *handle,
-                               struct ocfs2_dir_lookup_result *lookup)
-{
-        struct ocfs2_dx_root_block *dx_root;
-
-        dx_root = (struct ocfs2_dx_root_block *)lookup->dl_dx_root_bh->b_data;
-        if (ocfs2_dx_root_inline(dx_root))
-                return ocfs2_dx_inline_root_insert(dir, handle,
-                                                   &lookup->dl_hinfo,
-                                                   lookup->dl_leaf_bh->b_blocknr,
-                                                   lookup->dl_dx_root_bh);
-
-        return __ocfs2_dx_dir_leaf_insert(dir, handle, &lookup->dl_hinfo,
-                                          lookup->dl_leaf_bh->b_blocknr,
-                                          lookup->dl_dx_leaf_bh);
-}
-
 static void ocfs2_remove_block_from_free_list(struct inode *dir,
                                        handle_t *handle,
                                        struct ocfs2_dir_lookup_result *lookup)
@@ -2121,6 +2124,7 @@ struct ocfs2_empty_dir_priv {
         unsigned seen_dot;
         unsigned seen_dot_dot;
         unsigned seen_other;
+        unsigned dx_dir;
 };
 static int ocfs2_empty_dir_filldir(void *priv, const char *name, int name_len,
                                    loff_t pos, u64 ino, unsigned type)
@@ -2130,6 +2134,13 @@ static int ocfs2_empty_dir_filldir(void *priv, const char *name, int name_len,
         /*
          * Check the positions of "." and ".." records to be sure
          * they're in the correct place.
+         *
+         * Indexed directories don't need to proceed past the first
+         * two entries, so we end the scan after seeing '..'. Despite
+         * that, we allow the scan to proceed In the event that we
+         * have a corrupted indexed directory (no dot or dot dot
+         * entries). This allows us to double check for existing
+         * entries which might not have been found in the index.
          */
         if (name_len == 1 && !strncmp(".", name, 1) && pos == 0) {
                 p->seen_dot = 1;
@@ -2139,18 +2150,57 @@ static int ocfs2_empty_dir_filldir(void *priv, const char *name, int name_len,
         if (name_len == 2 && !strncmp("..", name, 2) &&
             pos == OCFS2_DIR_REC_LEN(1)) {
                 p->seen_dot_dot = 1;
+
+                if (p->dx_dir && p->seen_dot)
+                        return 1;
+
                 return 0;
         }
 
         p->seen_other = 1;
         return 1;
 }
+
+static int ocfs2_empty_dir_dx(struct inode *inode,
+                              struct ocfs2_empty_dir_priv *priv)
+{
+        int ret;
+        struct buffer_head *di_bh = NULL;
+        struct buffer_head *dx_root_bh = NULL;
+        struct ocfs2_dinode *di;
+        struct ocfs2_dx_root_block *dx_root;
+
+        priv->dx_dir = 1;
+
+        ret = ocfs2_read_inode_block(inode, &di_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+        di = (struct ocfs2_dinode *)di_bh->b_data;
+
+        ret = ocfs2_read_dx_root(inode, di, &dx_root_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+        dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
+
+        if (le32_to_cpu(dx_root->dr_num_entries) != 2)
+                priv->seen_other = 1;
+
+out:
+        brelse(di_bh);
+        brelse(dx_root_bh);
+        return ret;
+}
+
 /*
  * routine to check that the specified directory is empty (for rmdir)
  *
  * Returns 1 if dir is empty, zero otherwise.
  *
- * XXX: This is a performance problem
+ * XXX: This is a performance problem for unindexed directories.
  */
 int ocfs2_empty_dir(struct inode *inode)
 {
@@ -2160,6 +2210,16 @@ int ocfs2_empty_dir(struct inode *inode)
 
         memset(&priv, 0, sizeof(priv));
 
+        if (ocfs2_dir_indexed(inode)) {
+                ret = ocfs2_empty_dir_dx(inode, &priv);
+                if (ret)
+                        mlog_errno(ret);
+                /*
+                 * We still run ocfs2_dir_foreach to get the checks
+                 * for "." and "..".
+                 */
+        }
+
         ret = ocfs2_dir_foreach(inode, &start, &priv, ocfs2_empty_dir_filldir);
         if (ret)
                 mlog_errno(ret);
@@ -2329,7 +2389,7 @@ static int ocfs2_dx_dir_attach_index(struct ocfs2_super *osb,
                                      struct buffer_head *di_bh,
                                      struct buffer_head *dirdata_bh,
                                      struct ocfs2_alloc_context *meta_ac,
-                                     int dx_inline,
+                                     int dx_inline, u32 num_entries,
                                      struct buffer_head **ret_dx_root_bh)
 {
         int ret;
@@ -2375,6 +2435,7 @@ static int ocfs2_dx_dir_attach_index(struct ocfs2_super *osb,
         dx_root->dr_fs_generation = cpu_to_le32(osb->fs_generation);
         dx_root->dr_blkno = cpu_to_le64(dr_blkno);
         dx_root->dr_dir_blkno = cpu_to_le64(OCFS2_I(dir)->ip_blkno);
+        dx_root->dr_num_entries = cpu_to_le32(num_entries);
         if (le16_to_cpu(trailer->db_free_rec_len))
                 dx_root->dr_free_blk = cpu_to_le64(dirdata_bh->b_blocknr);
         else
@@ -2586,7 +2647,7 @@ static int ocfs2_fill_new_dir_dx(struct ocfs2_super *osb,
         }
 
         ret = ocfs2_dx_dir_attach_index(osb, handle, inode, di_bh, leaf_bh,
-                                        meta_ac, 1, &dx_root_bh);
+                                        meta_ac, 1, 2, &dx_root_bh);
         if (ret) {
                 mlog_errno(ret);
                 goto out;
@@ -2633,6 +2694,7 @@ static int ocfs2_dx_dir_index_block(struct inode *dir,
                                     handle_t *handle,
                                     struct buffer_head **dx_leaves,
                                     int num_dx_leaves,
+                                    u32 *num_dx_entries,
                                     struct buffer_head *dirent_bh)
 {
         int ret, namelen, i;
@@ -2664,6 +2726,8 @@ static int ocfs2_dx_dir_index_block(struct inode *dir,
                         goto out;
                 }
 
+                *num_dx_entries = *num_dx_entries + 1;
+
 inc:
                 de_buf += le16_to_cpu(de->rec_len);
         }
@@ -2707,6 +2771,8 @@ static void ocfs2_dx_dir_index_root_block(struct inode *dir,
 
                 ocfs2_dx_entry_list_insert(&dx_root->dr_entries, &hinfo,
                                            dirent_blk);
+
+                le32_add_cpu(&dx_root->dr_num_entries, 1);
 inc:
                 de_buf += le16_to_cpu(de->rec_len);
         }
@@ -2810,7 +2876,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
                                    struct ocfs2_dir_lookup_result *lookup,
                                    struct buffer_head **first_block_bh)
 {
-        u32 alloc, dx_alloc, bit_off, len;
+        u32 alloc, dx_alloc, bit_off, len, num_dx_entries = 0;
         struct super_block *sb = dir->i_sb;
         int ret, i, num_dx_leaves = 0, dx_inline = 0,
                 credits = ocfs2_inline_to_extents_credits(sb);
@@ -2972,10 +3038,14 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
                 /*
                  * Dx dirs with an external cluster need to do this up
                  * front. Inline dx root's get handled later, after
-                 * we've allocated our root block.
+                 * we've allocated our root block. We get passed back
+                 * a total number of items so that dr_num_entries can
+                 * be correctly set once the dx_root has been
+                 * allocated.
                  */
                 ret = ocfs2_dx_dir_index_block(dir, handle, dx_leaves,
-                                               num_dx_leaves, dirdata_bh);
+                                               num_dx_leaves, &num_dx_entries,
+                                               dirdata_bh);
                 if (ret) {
                         mlog_errno(ret);
                         goto out_commit;
@@ -3037,7 +3107,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
         if (ocfs2_supports_indexed_dirs(osb)) {
                 ret = ocfs2_dx_dir_attach_index(osb, handle, dir, di_bh,
                                                 dirdata_bh, meta_ac, dx_inline,
-                                                &dx_root_bh);
+                                                num_dx_entries, &dx_root_bh);
                 if (ret) {
                         mlog_errno(ret);
                         goto out_commit;
@@ -4202,6 +4272,12 @@ static int ocfs2_prepare_dx_dir_for_insert(struct inode *dir,
         }
 
         dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
+        if (le32_to_cpu(dx_root->dr_num_entries) == OCFS2_DX_ENTRIES_MAX) {
+                ret = -ENOSPC;
+                mlog_errno(ret);
+                goto out;
+        }
+
         if (ocfs2_dx_root_inline(dx_root)) {
                 ret = ocfs2_inline_dx_has_space(dx_root_bh);
 
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 43da76eff9a..f7a5201410c 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -421,6 +421,7 @@ static struct ocfs2_system_inode_info ocfs2_system_inodes[NUM_SYSTEM_INODES] = {
 #define OCFS2_LINK_MAX          32000
 #define OCFS2_DX_LINK_MAX       ((1U << 31) - 1U)
 #define OCFS2_LINKS_HI_SHIFT    16
+#define OCFS2_DX_ENTRIES_MAX    (0xffffffffU)
 
 #define S_SHIFT                 12
 static unsigned char ocfs2_type_by_mode[S_IFMT >> S_SHIFT] = {
@@ -844,7 +845,10 @@ struct ocfs2_dx_root_block {
         __u8            dr_reserved0;
         __le16          dr_reserved1;
         __le64          dr_dir_blkno;           /* Pointer to parent inode */
-        __le64          dr_reserved2;
+        __le32          dr_num_entries;         /* Total number of
+                                                 * names stored in
+                                                 * this directory.*/
+        __le32          dr_reserved2;
         __le64          dr_free_blk;            /* Pointer to head of free
                                                  * unindexed block list. */
         __le64          dr_reserved3[15];