Hi
"W. Wilson Ho" wrote:
>
> I now believe it is a reiserfs/kernel bug. I've managed to
> reproduce the bug in the following cases:
>
Ok, it appeared to be a known issue. When getting a problem do you have in your logs
something like:
"vs-: reiserfs_get_block: XXX YYY ZZZ UNKNOWN should not be found" or
"PAP-5710: reiserfs_paste_into_item: entry or pasted byte ([XXX YYY ZZZ UNKNOWN])
exists"?
If yes - you are hitting a problem known as "not perfect handling of race conditions
occuring during writing pages to a sparse file".
There are two fixes for this problem:
first is "expanding truncate" (although I am not sure which kernel it is for)
second changes reiserfs_get_block (patch against 2.4.8) to handle this race properly.
It is
probably less tested then the first one, it survives your mmap test for me though.
Thanks,
vs
--- 1.4/include/linux/fs.h Tue Jun 12 13:31:34 2001
+++ edited/include/linux/fs.h Mon Jun 18 00:21:16 2001
@@ -1316,6 +1316,9 @@
extern int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*);
extern int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*,
unsigned long *);
+
+int generic_cont_expand(struct inode *inode, loff_t size) ;
+
extern int block_sync_page(struct page *);
int generic_block_bmap(struct address_space *, long, get_block_t *);
--- 1.4/kernel/ksyms.c Mon Jun 11 15:15:27 2001
+++ edited/kernel/ksyms.c Sun Jun 17 22:56:05 2001
@@ -200,6 +200,7 @@
EXPORT_SYMBOL(block_read_full_page);
EXPORT_SYMBOL(block_prepare_write);
EXPORT_SYMBOL(block_sync_page);
+EXPORT_SYMBOL(generic_cont_expand);
EXPORT_SYMBOL(cont_prepare_write);
EXPORT_SYMBOL(generic_commit_write);
EXPORT_SYMBOL(block_truncate_page);
--- 1.4/fs/buffer.c Tue Jun 12 06:21:14 2001
+++ edited/fs/buffer.c Mon Jun 18 00:44:16 2001
@@ -1743,6 +1743,47 @@
return 0;
}
+int generic_cont_expand(struct inode *inode, loff_t size)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page;
+ unsigned long index, offset, limit;
+ int err;
+
+ limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
+ if (limit != RLIM_INFINITY) {
+ if (size > limit) {
+ send_sig(SIGXFSZ, current, 0);
+ size = limit;
+ }
+ }
+ offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */
+
+ /* ugh. in prepare/commit_write, if from==to==start of block, we
+ ** skip the prepare. make sure we never send an offset for the start
+ ** of a block
+ */
+ if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
+ offset++ ;
+ }
+ index = size >> PAGE_CACHE_SHIFT;
+ err = -ENOMEM;
+ page = grab_cache_page(mapping, index);
+ if (!page)
+ goto out;
+ err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
+ if (!err) {
+ char *p = page_address(page) ;
+ err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+ }
+ UnlockPage(page);
+ page_cache_release(page);
+ if (err > 0)
+ err = 0;
+out:
+ return err;
+}
+
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
--- 1.2/fs/reiserfs/file.c Sat Apr 28 11:27:17 2001
+++ edited/fs/reiserfs/file.c Mon Jun 18 01:00:33 2001
@@ -116,6 +116,13 @@
if (inode_items_version(inode) == ITEM_VERSION_1 &&
attr->ia_size > MAX_NON_LFS)
return -EFBIG ;
+
+ /* fill in hole pointers in the expanding truncate case. */
+ if (attr->ia_size > inode->i_size) {
+ error = generic_cont_expand(inode, attr->ia_size) ;
+ if (error)
+ return error ;
+ }
}
error = inode_change_ok(inode, attr) ;
--- 1.4/fs/reiserfs/inode.c Wed Jun 13 14:38:36 2001
+++ edited/fs/reiserfs/inode.c Sun Jun 17 23:23:47 2001
@@ -1959,7 +1959,7 @@
/* we test for O_SYNC here so we can commit the transaction
** for any packed tails the file might have had
*/
- if (f->f_flags & O_SYNC) {
+ if (f && (f->f_flags & O_SYNC)) {
journal_begin(&th, inode->i_sb, 1) ;
reiserfs_prepare_for_journal(inode->i_sb,
SB_BUFFER_WITH_SB(inode->i_sb), 1) ;
