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    Subject[PATCH 14/48] [GFS2] Introduce array of buffers to struct metapath
    Date
    From: Steven Whitehouse <swhiteho@redhat.com>

    The reason for doing this is to allow all the block mapping code
    to share the same array. As a result we can remove two arguments
    from lookup_metapath since they are now returned via the array.

    We also add a function to drop all refs to buffer heads when we
    are done with the metapath. The build_height function shares the
    struct metapath, but currently still frees its own buffers, and
    this will change in a future patch.

    Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

    diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
    index 08d1be4..2011dd2 100644
    --- a/fs/gfs2/bmap.c
    +++ b/fs/gfs2/bmap.c
    @@ -33,6 +33,7 @@
    * keep it small.
    */
    struct metapath {
    + struct buffer_head *mp_bh[GFS2_MAX_META_HEIGHT];
    __u16 mp_list[GFS2_MAX_META_HEIGHT];
    };

    @@ -185,12 +186,11 @@ out:
    * Returns: errno
    */

    -static int build_height(struct inode *inode, unsigned height)
    +static int build_height(struct inode *inode, struct metapath *mp, unsigned height)
    {
    struct gfs2_inode *ip = GFS2_I(inode);
    unsigned new_height = height - ip->i_height;
    struct buffer_head *dibh;
    - struct buffer_head *blocks[GFS2_MAX_META_HEIGHT];
    struct gfs2_dinode *di;
    int error;
    __be64 *bp;
    @@ -206,29 +206,29 @@ static int build_height(struct inode *inode, unsigned height)

    for(n = 0; n < new_height; n++) {
    bn = gfs2_alloc_meta(ip);
    - blocks[n] = gfs2_meta_new(ip->i_gl, bn);
    - gfs2_trans_add_bh(ip->i_gl, blocks[n], 1);
    + mp->mp_bh[n] = gfs2_meta_new(ip->i_gl, bn);
    + gfs2_trans_add_bh(ip->i_gl, mp->mp_bh[n], 1);
    }

    n = 0;
    - bn = blocks[0]->b_blocknr;
    + bn = mp->mp_bh[0]->b_blocknr;
    if (new_height > 1) {
    for(; n < new_height-1; n++) {
    - gfs2_metatype_set(blocks[n], GFS2_METATYPE_IN,
    + gfs2_metatype_set(mp->mp_bh[n], GFS2_METATYPE_IN,
    GFS2_FORMAT_IN);
    - gfs2_buffer_clear_tail(blocks[n],
    + gfs2_buffer_clear_tail(mp->mp_bh[n],
    sizeof(struct gfs2_meta_header));
    - bp = (__be64 *)(blocks[n]->b_data +
    + bp = (__be64 *)(mp->mp_bh[n]->b_data +
    sizeof(struct gfs2_meta_header));
    - *bp = cpu_to_be64(blocks[n+1]->b_blocknr);
    - brelse(blocks[n]);
    - blocks[n] = NULL;
    + *bp = cpu_to_be64(mp->mp_bh[n+1]->b_blocknr);
    + brelse(mp->mp_bh[n]);
    + mp->mp_bh[n] = NULL;
    }
    }
    - gfs2_metatype_set(blocks[n], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
    - gfs2_buffer_copy_tail(blocks[n], sizeof(struct gfs2_meta_header),
    + gfs2_metatype_set(mp->mp_bh[n], GFS2_METATYPE_IN, GFS2_FORMAT_IN);
    + gfs2_buffer_copy_tail(mp->mp_bh[n], sizeof(struct gfs2_meta_header),
    dibh, sizeof(struct gfs2_dinode));
    - brelse(blocks[n]);
    + brelse(mp->mp_bh[n]);
    gfs2_trans_add_bh(ip->i_gl, dibh, 1);
    di = (struct gfs2_dinode *)dibh->b_data;
    gfs2_buffer_clear_tail(dibh, sizeof(struct gfs2_dinode));
    @@ -314,7 +314,6 @@ static void find_metapath(struct gfs2_inode *ip, u64 block,

    /**
    * metapointer - Return pointer to start of metadata in a buffer
    - * @bh: The buffer
    * @height: The metadata height (0 = dinode)
    * @mp: The metapath
    *
    @@ -323,9 +322,10 @@ static void find_metapath(struct gfs2_inode *ip, u64 block,
    * metadata tree.
    */

    -static inline __be64 *metapointer(struct buffer_head *bh, int *boundary,
    - unsigned int height, const struct metapath *mp)
    +static inline __be64 *metapointer(int *boundary, unsigned int height,
    + const struct metapath *mp)
    {
    + struct buffer_head *bh = mp->mp_bh[height];
    unsigned int head_size = (height > 0) ?
    sizeof(struct gfs2_meta_header) : sizeof(struct gfs2_dinode);
    __be64 *ptr;
    @@ -339,7 +339,6 @@ static inline __be64 *metapointer(struct buffer_head *bh, int *boundary,
    /**
    * lookup_block - Get the next metadata block in metadata tree
    * @ip: The GFS2 inode
    - * @bh: Buffer containing the pointers to metadata blocks
    * @height: The height of the tree (0 = dinode)
    * @mp: The metapath
    * @create: Non-zero if we may create a new meatdata block
    @@ -352,12 +351,12 @@ static inline __be64 *metapointer(struct buffer_head *bh, int *boundary,
    *
    */

    -static int lookup_block(struct gfs2_inode *ip, struct buffer_head *bh,
    - unsigned int height, struct metapath *mp, int create,
    +static int lookup_block(struct gfs2_inode *ip, unsigned int height,
    + struct metapath *mp, int create,
    int *new, u64 *block)
    {
    int boundary;
    - __be64 *ptr = metapointer(bh, &boundary, height, mp);
    + __be64 *ptr = metapointer(&boundary, height, mp);

    if (*ptr) {
    *block = be64_to_cpu(*ptr);
    @@ -374,7 +373,7 @@ static int lookup_block(struct gfs2_inode *ip, struct buffer_head *bh,
    else
    *block = gfs2_alloc_meta(ip);

    - gfs2_trans_add_bh(ip->i_gl, bh, 1);
    + gfs2_trans_add_bh(ip->i_gl, mp->mp_bh[height], 1);

    *ptr = cpu_to_be64(*block);
    ip->i_di.di_blocks++;
    @@ -385,32 +384,38 @@ static int lookup_block(struct gfs2_inode *ip, struct buffer_head *bh,
    }

    static int lookup_metapath(struct inode *inode, struct metapath *mp,
    - int create, int *new, u64 *dblock,
    - struct buffer_head **dibh, struct buffer_head **bh)
    + int create, int *new, u64 *dblock)
    {
    + struct buffer_head *bh;
    struct gfs2_inode *ip = GFS2_I(inode);
    unsigned int end_of_metadata = ip->i_height - 1;
    unsigned int x;
    - int ret = gfs2_meta_inode_buffer(ip, bh);
    + int ret = gfs2_meta_inode_buffer(ip, &bh);
    if (ret)
    return ret;

    - *dibh = *bh;
    - get_bh(*dibh);
    + mp->mp_bh[0] = bh;

    for (x = 0; x < end_of_metadata; x++) {
    - lookup_block(ip, *bh, x, mp, create, new, dblock);
    - brelse(*bh);
    - *bh = NULL;
    + lookup_block(ip, x, mp, create, new, dblock);
    if (!dblock)
    return 0;

    - ret = gfs2_meta_indirect_buffer(ip, x+1, *dblock, *new, bh);
    + ret = gfs2_meta_indirect_buffer(ip, x+1, *dblock, *new, &mp->mp_bh[x+1]);
    if (ret)
    return ret;
    }

    - return lookup_block(ip, *bh, end_of_metadata, mp, create, new, dblock);
    + return lookup_block(ip, end_of_metadata, mp, create, new, dblock);
    +}
    +
    +static void release_metapath(struct metapath *mp)
    +{
    + int i;
    +
    + for (i = 0; i < GFS2_MAX_META_HEIGHT; i++)
    + if (mp->mp_bh[i])
    + brelse(mp->mp_bh[i]);
    }

    static inline void bmap_lock(struct inode *inode, int create)
    @@ -449,7 +454,6 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
    struct gfs2_inode *ip = GFS2_I(inode);
    struct gfs2_sbd *sdp = GFS2_SB(inode);
    unsigned int bsize = sdp->sd_sb.sb_bsize;
    - struct buffer_head *bh = NULL;
    int error = 0;
    int new = 0;
    u64 dblock = 0;
    @@ -457,13 +461,13 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
    unsigned int maxlen = bh_map->b_size >> inode->i_blkbits;
    struct metapath mp;
    u64 size;
    - struct buffer_head *dibh = NULL;
    const u64 *arr = sdp->sd_heightsize;
    BUG_ON(maxlen == 0);

    if (gfs2_assert_warn(sdp, !gfs2_is_stuffed(ip)))
    return 0;

    + memset(mp.mp_bh, 0, sizeof(mp.mp_bh));
    bmap_lock(inode, create);
    clear_buffer_mapped(bh_map);
    clear_buffer_new(bh_map);
    @@ -480,13 +484,13 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
    goto out_ok;
    while (size > arr[height])
    height++;
    - error = build_height(inode, height);
    + error = build_height(inode, &mp, height);
    if (error)
    goto out_fail;
    }

    find_metapath(ip, lblock, &mp);
    - error = lookup_metapath(inode, &mp, create, &new, &dblock, &dibh, &bh);
    + error = lookup_metapath(inode, &mp, create, &new, &dblock);
    if (error < 0)
    goto out_fail;
    boundary = error;
    @@ -496,17 +500,15 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
    if (boundary)
    set_buffer_boundary(bh_map);
    if (new) {
    - gfs2_trans_add_bh(ip->i_gl, dibh, 1);
    - gfs2_dinode_out(ip, dibh->b_data);
    + gfs2_trans_add_bh(ip->i_gl, mp.mp_bh[0], 1);
    + gfs2_dinode_out(ip, mp.mp_bh[0]->b_data);
    set_buffer_new(bh_map);
    - goto out_brelse;
    + goto out_ok;
    }
    while(--maxlen && !buffer_boundary(bh_map)) {
    - unsigned int end_of_metadata = ip->i_height - 1;
    u64 eblock;
    -
    - mp.mp_list[end_of_metadata]++;
    - boundary = lookup_block(ip, bh, end_of_metadata, &mp, 0, &new, &eblock);
    + mp.mp_list[ip->i_height - 1]++;
    + boundary = lookup_block(ip, ip->i_height - 1, &mp, 0, &new, &eblock);
    if (eblock != ++dblock)
    break;
    bh_map->b_size += (1 << inode->i_blkbits);
    @@ -514,14 +516,10 @@ int gfs2_block_map(struct inode *inode, sector_t lblock,
    set_buffer_boundary(bh_map);
    }
    }
    -out_brelse:
    - if (bh)
    - brelse(bh);
    out_ok:
    error = 0;
    out_fail:
    - if (dibh)
    - brelse(dibh);
    + release_metapath(&mp);
    bmap_unlock(inode, create);
    return error;
    }
    @@ -819,10 +817,11 @@ static int do_grow(struct gfs2_inode *ip, u64 size)

    down_write(&ip->i_rw_mutex);
    if (size > arr[ip->i_height]) {
    + struct metapath mp;
    u8 height = ip->i_height;
    while(size > arr[height])
    height++;
    - error = build_height(&ip->i_inode, height);
    + error = build_height(&ip->i_inode, &mp, height);
    }
    up_write(&ip->i_rw_mutex);
    if (error)
    --
    1.5.1.2


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