This patch added support of mapping multiple blocks in one short.
This is useful for DIO reads and re-writes (where blocks are already allocated),
also is in line with Christoph's proposal of using getblocks() in
mpage_readpage() or mpage_readpages().
Signed-off-by: Mingming Cao <[email protected]>
---
linux-2.6.15-ming/fs/ext3/inode.c | 91 ++++++++++++++++++++++++++------------
1 files changed, 64 insertions(+), 27 deletions(-)
diff -puN fs/ext3/inode.c~ext3-map-mblocks fs/ext3/inode.c
--- linux-2.6.15/fs/ext3/inode.c~ext3-map-mblocks 2006-01-09 14:17:04.000000000 -0800
+++ linux-2.6.15-ming/fs/ext3/inode.c 2006-01-09 16:47:47.000000000 -0800
@@ -330,7 +330,7 @@ static int ext3_block_to_path(struct ino
ext3_warning (inode->i_sb, "ext3_block_to_path", "block > big");
}
if (boundary)
- *boundary = (i_block & (ptrs - 1)) == (final - 1);
+ *boundary = final - 1 - (i_block & (ptrs - 1));
return n;
}
@@ -669,11 +669,14 @@ err_out:
* akpm: `handle' can be NULL if create == 0.
*
* The BKL may not be held on entry here. Be sure to take it early.
+ * return > 0, # of blocks mapped or allocated
+ * return < 0, error case
*/
static int
-ext3_get_block_handle(handle_t *handle, struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create, int extend_disksize)
+ext3_get_blocks_handle(handle_t *handle, struct inode *inode, sector_t iblock,
+ unsigned long maxblocks, struct buffer_head *bh_result,
+ int create, int extend_disksize)
{
int err = -EIO;
int offsets[4];
@@ -681,11 +684,15 @@ ext3_get_block_handle(handle_t *handle,
Indirect *partial;
unsigned long goal;
int left;
- int boundary = 0;
- const int depth = ext3_block_to_path(inode, iblock, offsets, &boundary);
+ int blocks_to_boundary = 0;
+ int depth;
struct ext3_inode_info *ei = EXT3_I(inode);
+ int count = 0;
+ unsigned long first_block = 0;
+
J_ASSERT(handle != NULL || create == 0);
+ depth = ext3_block_to_path(inode, iblock, offsets, &blocks_to_boundary);
if (depth == 0)
goto out;
@@ -694,7 +701,29 @@ ext3_get_block_handle(handle_t *handle,
/* Simplest case - block found, no allocation needed */
if (!partial) {
+ first_block = chain[depth-1].key;
clear_buffer_new(bh_result);
+ count++;
+ /*map more blocks*/
+ while (count < maxblocks && count <= blocks_to_boundary) {
+ if (!verify_chain(chain, partial)) {
+ /*
+ * Indirect block might be removed by
+ * truncate while we were reading it.
+ * Handling of that case: forget what we've
+ * got now. Flag the err as EAGAIN, so it
+ * will reread.
+ */
+ err = -EAGAIN;
+ count = 0;
+ break;
+ }
+ if (le32_to_cpu(*(chain[depth-1].p+count) ==
+ (first_block + count)))
+ count++;
+ else
+ break;
+ }
goto got_it;
}
@@ -723,6 +752,7 @@ ext3_get_block_handle(handle_t *handle,
}
partial = ext3_get_branch(inode, depth, offsets, chain, &err);
if (!partial) {
+ count++;
up(&ei->truncate_sem);
if (err)
goto cleanup;
@@ -772,8 +802,9 @@ ext3_get_block_handle(handle_t *handle,
set_buffer_new(bh_result);
got_it:
map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
- if (boundary)
+ if (blocks_to_boundary == 0)
set_buffer_boundary(bh_result);
+ err = count;
/* Clean up and exit */
partial = chain + depth - 1; /* the whole chain */
cleanup:
@@ -787,21 +818,6 @@ out:
return err;
}
-static int ext3_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
-{
- handle_t *handle = NULL;
- int ret;
-
- if (create) {
- handle = ext3_journal_current_handle();
- J_ASSERT(handle != 0);
- }
- ret = ext3_get_block_handle(handle, inode, iblock,
- bh_result, create, 1);
- return ret;
-}
-
#define DIO_CREDITS (EXT3_RESERVE_TRANS_BLOCKS + 32)
static int
@@ -815,6 +831,9 @@ ext3_direct_io_get_blocks(struct inode *
if (!handle)
goto get_block; /* A read */
+ if (max_blocks == 1)
+ goto get_block; /* A single block get */
+
if (handle->h_transaction->t_state == T_LOCKED) {
/*
* Huge direct-io writes can hold off commits for long
@@ -841,13 +860,31 @@ ext3_direct_io_get_blocks(struct inode *
}
get_block:
- if (ret == 0)
- ret = ext3_get_block_handle(handle, inode, iblock,
- bh_result, create, 0);
- bh_result->b_size = (1 << inode->i_blkbits);
+ if (ret == 0) {
+ ret = ext3_get_blocks_handle(handle, inode, iblock,
+ max_blocks, bh_result, create, 0);
+ if (ret > 0) {
+ bh_result->b_size = (ret << inode->i_blkbits);
+ ret = 0;
+ }
+ }
return ret;
}
+static int ext3_get_blocks(struct inode *inode, sector_t iblock,
+ unsigned long maxblocks, struct buffer_head *bh_result,
+ int create)
+{
+ return ext3_direct_io_get_blocks(inode, iblock, maxblocks,
+ bh_result, create);
+}
+
+static int ext3_get_block(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ return ext3_get_blocks(inode, iblock, 1, bh_result, create);
+}
+
/*
* `handle' can be NULL if create is zero
*/
@@ -862,8 +899,8 @@ struct buffer_head *ext3_getblk(handle_t
dummy.b_state = 0;
dummy.b_blocknr = -1000;
buffer_trace_init(&dummy.b_history);
- *errp = ext3_get_block_handle(handle, inode, block, &dummy, create, 1);
- if (!*errp && buffer_mapped(&dummy)) {
+ *errp = ext3_get_blocks_handle(handle, inode, block, 1, &dummy, create, 1);
+ if ((*errp == 1 ) && buffer_mapped(&dummy)) {
struct buffer_head *bh;
bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
if (!bh) {
_