Messages in this thread Patch in this message |  | | Date | Wed, 6 Dec 2000 03:03:12 -0500 (EST) | From | Alexander Viro <> | Subject | [PATCH] Re: test12-pre6 |
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If get_block() fails in block_prepare_write() we should zero the blocks we've allocated and mark them dirty. We don't (i.e. we leave the random junk in file in that case). Fix: do it. Moreover, if ->prepare_write() fails generic_file_write() is not going to write the user's data into that page. It's OK if we were in hole (we got zeroes in all new blocks, so it's equivalent to doing nothing with that page), but it's not OK if we extended the file (we would get the file silently extended with zeroes we've never intended to write there or we would get blocks allocated past the ->i_size - the former screws applications, the latter makes fsck unhappy). Fix: if the failed call extended the file call vmtruncate() to clean the mess up.
Please, apply.
diff -urN rc12-pre6/fs/buffer.c rc12-pre6-get_block/fs/buffer.c --- rc12-pre6/fs/buffer.c Tue Dec 5 02:03:14 2000 +++ rc12-pre6-get_block/fs/buffer.c Tue Dec 5 14:56:20 2000 @@ -1710,6 +1710,15 @@ } return 0; out: + bh = head; + do { + if (buffer_new(bh) && !buffer_uptodate(bh)) { + memset(bh->b_data, 0, bh->b_size); + set_bit(BH_Uptodate, &bh->b_state); + mark_buffer_dirty(bh); + } + bh = bh->b_this_page; + } while (bh != head); return err; } diff -urN rc12-pre6/mm/filemap.c rc12-pre6-get_block/mm/filemap.c --- rc12-pre6/mm/filemap.c Tue Dec 5 02:03:20 2000 +++ rc12-pre6-get_block/mm/filemap.c Tue Dec 5 14:56:20 2000 @@ -2382,6 +2382,7 @@ unsigned long written; long status; int err; + unsigned bytes; cached_page = NULL; @@ -2426,7 +2427,7 @@ } while (count) { - unsigned long bytes, index, offset; + unsigned long index, offset; char *kaddr; /* @@ -2451,7 +2452,7 @@ status = mapping->a_ops->prepare_write(file, page, offset, offset+bytes); if (status) - goto unlock; + goto sync_failure; kaddr = page_address(page); status = copy_from_user(kaddr+offset, buf, bytes); flush_dcache_page(page); @@ -2476,6 +2477,7 @@ if (status < 0) break; } +done: *ppos = pos; if (cached_page) @@ -2496,6 +2498,13 @@ ClearPageUptodate(page); kunmap(page); goto unlock; +sync_failure: + UnlockPage(page); + deactivate_page(page); + page_cache_release(page); + if (pos + bytes > inode->i_size) + vmtruncate(inode, inode->i_size); + goto done; } void __init page_cache_init(unsigned long mempages)
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