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SubjectRe: [reiserfs-dev] Re: [PATCH] expanding truncate


On Friday, January 04, 2002 12:33:32 PM -0500 Chris Mason <mason@suse.com> wrote:

[ expanding truncate patch ]

>> Seriously, it looks like a half-arsed and very old attempt to do common
>> expanding truncate() for no-holes filesystems. BTW, these days rlimit
>> checks are done by vmtruncate().

Ok, the rlimit checks where still there because generic_cont_expand is called before vmtruncate. I changed it around to match vmtruncate better though.

Does anyone still object to the patch below?

-chris

--- 0.22/fs/reiserfs/file.c Fri, 11 Jan 2002 14:17:09 -0500
+++ 0.22(w)/fs/reiserfs/file.c Fri, 11 Jan 2002 15:28:35 -0500
@@ -103,6 +103,20 @@
if (get_inode_item_key_version(inode) == KEY_FORMAT_3_5 &&
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 (inode->u.reiserfs_i.i_prealloc_count > 0) {
+ struct reiserfs_transaction_handle th ;
+ /* we're changing at most 2 bitmaps, inode + super */
+ journal_begin(&th, inode->i_sb, 4) ;
+ reiserfs_discard_prealloc (&th, inode);
+ journal_end(&th, inode->i_sb, 4) ;
+ }
+ if (error)
+ return error ;
+ }
}

if ((((attr->ia_valid & ATTR_UID) && (attr->ia_uid & ~0xffff)) ||
--- 0.22/fs/reiserfs/inode.c Fri, 11 Jan 2002 14:17:09 -0500
+++ 0.22(w)/fs/reiserfs/inode.c Fri, 11 Jan 2002 14:43:42 -0500
@@ -2125,7 +2125,7 @@
/* 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) {
lock_kernel() ;
reiserfs_commit_for_inode(inode) ;
unlock_kernel();
--- 0.22/fs/buffer.c Fri, 11 Jan 2002 11:53:37 -0500
+++ 0.22(w)/fs/buffer.c Fri, 11 Jan 2002 15:28:08 -0500
@@ -1760,6 +1760,52 @@
return 0;
}

+/* utility function for filesystems that need to do work on expanding
+ * truncates. Uses prepare/commit_write to allow the filesystem to
+ * deal with the hole.
+ */
+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;
+
+ err = -EFBIG;
+ limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
+ if (limit != RLIM_INFINITY && size > (loff_t)limit) {
+ send_sig(SIGXFSZ, current, 0);
+ goto out;
+ }
+ if (size > inode->i_sb->s_maxbytes)
+ goto out;
+
+ 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) {
+ 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.
--- 0.22/kernel/ksyms.c Fri, 11 Jan 2002 11:54:05 -0500
+++ 0.22(w)/kernel/ksyms.c Fri, 11 Jan 2002 14:17:35 -0500
@@ -204,6 +204,7 @@
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);
--- 0.22/include/linux/fs.h Fri, 11 Jan 2002 14:17:09 -0500
+++ 0.22(w)/include/linux/fs.h Fri, 11 Jan 2002 14:17:35 -0500
@@ -1416,6 +1416,7 @@
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 *);
+extern int generic_cont_expand(struct inode *inode, loff_t size) ;
extern int block_commit_write(struct page *page, unsigned from, unsigned to);
extern int block_sync_page(struct page *);


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