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Go Back   Linux Archive > Redhat > Cluster Development

 
 
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Old 04-17-2008, 08:38 AM
 
Default Introduce array of buffers to struct metapath

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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