GFS2: Make height info part of metapath

This patch eliminates height parameters from function gfs2_bmap_alloc.
Function find_metapath determines the metapath's "find height", also
known as the desired height. Function lookup_metapath determines the
metapath's "actual height", previously known as starting height or
sheight. Function gfs2_bmap_alloc now gets both height values from
the metapath. This simplification was done as a step toward switching
the block_map functions to using iomap. The bh_map responsibilities
are also removed from function gfs2_bmap_alloc for the same reason.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 8830e2903a349df89ee2a904ca17bed5d61a10e6..03badc8417d7f3aff171a2e390cdfd8ac97285f1 100644 (file)
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -36,6 +36,8 @@
 struct metapath {
        struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
        __u16 mp_list[GFS2_MAX_META_HEIGHT];
+       int mp_fheight; /* find_metapath height */
+       int mp_aheight; /* actual height (lookup height) */
 };
 
 /**
@@ -235,9 +237,9 @@ static void find_metapath(const struct gfs2_sbd *sdp, u64 block,
 {
        unsigned int i;
 
+       mp->mp_fheight = height;
        for (i = height; i--;)
                mp->mp_list[i] = do_div(block, sdp->sd_inptrs);
-
 }
 
 static inline unsigned int metapath_branch_start(const struct metapath *mp)
@@ -345,10 +347,13 @@ static int lookup_metapath(struct gfs2_inode *ip, struct metapath *mp)
        for (x = 0; x < end_of_metadata; x++) {
                ret = lookup_mp_height(ip, mp, x);
                if (ret)
-                       return ret;
+                       goto out;
        }
 
-       return ip->i_height;
+       ret = ip->i_height;
+out:
+       mp->mp_aheight = ret;
+       return ret;
 }
 
 /**
@@ -480,10 +485,11 @@ static inline unsigned int hptrs(struct gfs2_sbd *sdp, const unsigned int hgt)
  * @inode: The GFS2 inode
  * @lblock: The logical starting block of the extent
  * @bh_map: This is used to return the mapping details
- * @mp: The metapath
- * @sheight: The starting height (i.e. whats already mapped)
- * @height: The height to build to
+ * @zero_new: True if newly allocated blocks should be zeroed
+ * @mp: The metapath, with proper height information calculated
  * @maxlen: The max number of data blocks to alloc
+ * @dblock: Pointer to return the resulting new block
+ * @dblks: Pointer to return the number of blocks allocated
  *
  * In this routine we may have to alloc:
  *   i) Indirect blocks to grow the metadata tree height
@@ -500,62 +506,63 @@ static inline unsigned int hptrs(struct gfs2_sbd *sdp, const unsigned int hgt)
  */
 
 static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
-                          struct buffer_head *bh_map, struct metapath *mp,
-                          const unsigned int sheight,
-                          const unsigned int height,
-                          const size_t maxlen)
+                          bool zero_new, struct metapath *mp,
+                          const size_t maxlen, sector_t *dblock,
+                          unsigned *dblks)
 {
        struct gfs2_inode *ip = GFS2_I(inode);
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct super_block *sb = sdp->sd_vfs;
        struct buffer_head *dibh = mp->mp_bh[0];
-       u64 bn, dblock = 0;
+       u64 bn;
        unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
-       unsigned dblks = 0;
        unsigned ptrs_per_blk;
-       const unsigned end_of_metadata = height - 1;
+       const unsigned end_of_metadata = mp->mp_fheight - 1;
        int ret;
        int eob = 0;
        enum alloc_state state;
        __be64 *ptr;
        __be64 zero_bn = 0;
 
-       BUG_ON(sheight < 1);
+       BUG_ON(mp->mp_aheight < 1);
        BUG_ON(dibh == NULL);
 
+       *dblock = 0;
+       *dblks = 0;
        gfs2_trans_add_meta(ip->i_gl, dibh);
 
-       if (height == sheight) {
+       if (mp->mp_fheight == mp->mp_aheight) {
                struct buffer_head *bh;
                /* Bottom indirect block exists, find unalloced extent size */
                ptr = metapointer(end_of_metadata, mp);
                bh = mp->mp_bh[end_of_metadata];
-               dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr, maxlen,
-                                          &eob);
-               BUG_ON(dblks < 1);
+               *dblks = gfs2_extent_length(bh->b_data, bh->b_size, ptr,
+                                           maxlen, &eob);
+               BUG_ON(*dblks < 1);
                state = ALLOC_DATA;
        } else {
                /* Need to allocate indirect blocks */
-               ptrs_per_blk = height > 1 ? sdp->sd_inptrs : sdp->sd_diptrs;
-               dblks = min(maxlen, (size_t)(ptrs_per_blk -
-                                            mp->mp_list[end_of_metadata]));
-               if (height == ip->i_height) {
+               ptrs_per_blk = mp->mp_fheight > 1 ? sdp->sd_inptrs :
+                       sdp->sd_diptrs;
+               *dblks = min(maxlen, (size_t)(ptrs_per_blk -
+                                             mp->mp_list[end_of_metadata]));
+               if (mp->mp_fheight == ip->i_height) {
                        /* Writing into existing tree, extend tree down */
-                       iblks = height - sheight;
+                       iblks = mp->mp_fheight - mp->mp_aheight;
                        state = ALLOC_GROW_DEPTH;
                } else {
                        /* Building up tree height */
                        state = ALLOC_GROW_HEIGHT;
-                       iblks = height - ip->i_height;
+                       iblks = mp->mp_fheight - ip->i_height;
                        branch_start = metapath_branch_start(mp);
-                       iblks += (height - branch_start);
+                       iblks += (mp->mp_fheight - branch_start);
                }
        }
 
        /* start of the second part of the function (state machine) */
 
-       blks = dblks + iblks;
-       i = sheight;
+       blks = *dblks + iblks;
+       i = mp->mp_aheight;
        do {
                int error;
                n = blks - alloced;
@@ -573,9 +580,10 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
                                                 sizeof(struct gfs2_dinode));
                                zero_bn = *ptr;
                        }
-                       for (; i - 1 < height - ip->i_height && n > 0; i++, n--)
+                       for (; i - 1 < mp->mp_fheight - ip->i_height && n > 0;
+                            i++, n--)
                                gfs2_indirect_init(mp, ip->i_gl, i, 0, bn++);
-                       if (i - 1 == height - ip->i_height) {
+                       if (i - 1 == mp->mp_fheight - ip->i_height) {
                                i--;
                                gfs2_buffer_copy_tail(mp->mp_bh[i],
                                                sizeof(struct gfs2_meta_header),
@@ -587,7 +595,7 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
                                        sizeof(struct gfs2_meta_header));
                                *ptr = zero_bn;
                                state = ALLOC_GROW_DEPTH;
-                               for(i = branch_start; i < height; i++) {
+                               for(i = branch_start; i < mp->mp_fheight; i++) {
                                        if (mp->mp_bh[i] == NULL)
                                                break;
                                        brelse(mp->mp_bh[i]);
@@ -599,44 +607,40 @@ static int gfs2_bmap_alloc(struct inode *inode, const sector_t lblock,
                                break;
                /* Branching from existing tree */
                case ALLOC_GROW_DEPTH:
-                       if (i > 1 && i < height)
+                       if (i > 1 && i < mp->mp_fheight)
                                gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[i-1]);
-                       for (; i < height && n > 0; i++, n--)
+                       for (; i < mp->mp_fheight && n > 0; i++, n--)
                                gfs2_indirect_init(mp, ip->i_gl, i,
                                                   mp->mp_list[i-1], bn++);
-                       if (i == height)
+                       if (i == mp->mp_fheight)
                                state = ALLOC_DATA;
                        if (n == 0)
                                break;
                /* Tree complete, adding data blocks */
                case ALLOC_DATA:
-                       BUG_ON(n > dblks);
+                       BUG_ON(n > *dblks);
                        BUG_ON(mp->mp_bh[end_of_metadata] == NULL);
                        gfs2_trans_add_meta(ip->i_gl, mp->mp_bh[end_of_metadata]);
-                       dblks = n;
+                       *dblks = n;
                        ptr = metapointer(end_of_metadata, mp);
-                       dblock = bn;
+                       *dblock = bn;
                        while (n-- > 0)
                                *ptr++ = cpu_to_be64(bn++);
-                       if (buffer_zeronew(bh_map)) {
-                               ret = sb_issue_zeroout(sb, dblock, dblks,
+                       if (zero_new) {
+                               ret = sb_issue_zeroout(sb, *dblock, *dblks,
                                                       GFP_NOFS);
                                if (ret) {
                                        fs_err(sdp,
                                               "Failed to zero data buffers\n");
-                                       clear_buffer_zeronew(bh_map);
                                }
                        }
                        break;
                }
-       } while ((state != ALLOC_DATA) || !dblock);
+       } while ((state != ALLOC_DATA) || !(*dblock));
 
-       ip->i_height = height;
+       ip->i_height = mp->mp_fheight;
        gfs2_add_inode_blocks(&ip->i_inode, alloced);
        gfs2_dinode_out(ip, mp->mp_bh[0]->b_data);
-       map_bh(bh_map, inode->i_sb, dblock);
-       bh_map->b_size = dblks << inode->i_blkbits;
-       set_buffer_new(bh_map);
        return 0;
 }
 
@@ -670,6 +674,9 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
        unsigned int len;
        struct buffer_head *bh;
        u8 height;
+       bool zero_new = false;
+       sector_t dblock = 0;
+       unsigned dblks;
 
        BUG_ON(maxlen == 0);
 
@@ -699,13 +706,13 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
        while (size > arr[height])
                height++;
        find_metapath(sdp, lblock, &mp, height);
-       ret = 1;
+       mp.mp_aheight = 1;
        if (height > ip->i_height || gfs2_is_stuffed(ip))
                goto do_alloc;
        ret = lookup_metapath(ip, &mp);
        if (ret < 0)
                goto out;
-       if (ret != ip->i_height)
+       if (mp.mp_aheight != ip->i_height)
                goto do_alloc;
        ptr = metapointer(ip->i_height - 1, &mp);
        if (*ptr == 0)
@@ -732,7 +739,15 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
        }
 
        /* At this point ret is the tree depth of already allocated blocks */
-       ret = gfs2_bmap_alloc(inode, lblock, bh_map, &mp, ret, height, maxlen);
+       if (buffer_zeronew(bh_map))
+               zero_new = true;
+       ret = gfs2_bmap_alloc(inode, lblock, zero_new, &mp, maxlen, &dblock,
+                             &dblks);
+       if (ret == 0) {
+               map_bh(bh_map, inode->i_sb, dblock);
+               bh_map->b_size = dblks << inode->i_blkbits;
+               set_buffer_new(bh_map);
+       }
        goto out;
 }