[patch 10/12] direct IO fixes

Andrew Morton (akpm@zip.com.au)
Fri, 09 Aug 2002 17:57:58 -0700


Some direct IO fixes from Badari Pulavarty.

- off-by-one in the bounds checking in blkdev_get_blocks().

- When adding more blocks into a bio_vec, account for the current
offset into that bio_vec.

- Fix a total ballsup in the code which calculates the total number
of pages which are about to be put under IO.

block_dev.c | 2 +-
direct-io.c | 7 ++++---
2 files changed, 5 insertions, 4 deletions

--- 2.5.30/fs/direct-io.c~direct_io-fixes Fri Aug 9 17:36:47 2002
+++ 2.5.30-akpm/fs/direct-io.c Fri Aug 9 17:36:47 2002
@@ -489,7 +489,7 @@ int do_direct_IO(struct dio *dio)

/* Work out how much disk we can add to this page */
this_chunk_blocks = dio->blocks_available;
- u = (PAGE_SIZE - dio->bvec->bv_len) >> blkbits;
+ u = (PAGE_SIZE - (dio->bvec->bv_offset + dio->bvec->bv_len)) >> blkbits;
if (this_chunk_blocks > u)
this_chunk_blocks = u;
u = dio->final_block_in_request - dio->block_in_file;
@@ -567,10 +567,11 @@ generic_direct_IO(int rw, struct inode *
dio.curr_page = 0;
bytes = count;
dio.total_pages = 0;
- if (offset & PAGE_SIZE) {
+ if (user_addr & (PAGE_SIZE - 1)) {
dio.total_pages++;
- bytes -= PAGE_SIZE - (offset & ~(PAGE_SIZE - 1));
+ bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1));
}
+
dio.total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
dio.curr_user_address = user_addr;

--- 2.5.30/fs/block_dev.c~direct_io-fixes Fri Aug 9 17:36:47 2002
+++ 2.5.30-akpm/fs/block_dev.c Fri Aug 9 17:36:47 2002
@@ -105,7 +105,7 @@ static int
blkdev_get_blocks(struct inode *inode, sector_t iblock,
unsigned long max_blocks, struct buffer_head *bh, int create)
{
- if ((iblock + max_blocks) >= max_block(inode->i_bdev))
+ if ((iblock + max_blocks) > max_block(inode->i_bdev))
return -EIO;

bh->b_bdev = inode->i_bdev;

.
-
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