[PATCH] ufs: truncate should allocate block for last byte

This patch fixes buggy behaviour of UFS
in such kind of scenario:
open(, O_TRUNC...)
ftruncate(, 1024)
ftruncate(, 0)

Such a scenario causes ufs_panic and remount read-only.  This happen
because of according to specification UFS should always allocate block for
last byte, and many parts of our implementation rely on this, but
`ufs_truncate' doesn't care about this.

To make possible return error code and to know about old size, this patch
removes `truncate' from ufs inode_operations and uses `setattr' method to
call ufs_truncate.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 204 insertions, 65 deletions

diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
index 95b878e5c7a0..b01804baa120 100644
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -217,48 +217,6 @@ failed:
         return;
 }
 
-static struct page *ufs_get_locked_page(struct address_space *mapping,
-                                  unsigned long index)
-{
-        struct page *page;
-
-try_again:
-        page = find_lock_page(mapping, index);
-        if (!page) {
-                page = read_cache_page(mapping, index,
-                                       (filler_t*)mapping->a_ops->readpage,
-                                       NULL);
-                if (IS_ERR(page)) {
-                        printk(KERN_ERR "ufs_change_blocknr: "
-                               "read_cache_page error: ino %lu, index: %lu\n",
-                               mapping->host->i_ino, index);
-                        goto out;
-                }
-
-                lock_page(page);
-
-                if (!PageUptodate(page) || PageError(page)) {
-                        unlock_page(page);
-                        page_cache_release(page);
-
-                        printk(KERN_ERR "ufs_change_blocknr: "
-                               "can not read page: ino %lu, index: %lu\n",
-                               mapping->host->i_ino, index);
-
-                        page = ERR_PTR(-EIO);
-                        goto out;
-                }
-        }
-
-        if (unlikely(!page->mapping || !page_has_buffers(page))) {
-                unlock_page(page);
-                page_cache_release(page);
-                goto try_again;/*we really need these buffers*/
-        }
-out:
-        return page;
-}
-
 /*
  * Modify inode page cache in such way:
  * have - blocks with b_blocknr equal to oldb...oldb+count-1
@@ -311,10 +269,8 @@ static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk,
 
                 set_page_dirty(page);
 
-                if (likely(cur_index != index)) {
-                        unlock_page(page);
-                        page_cache_release(page);
-                }
+                if (likely(cur_index != index))
+                        ufs_put_locked_page(page);
         }
         UFSD("EXIT\n");
 }
diff --git a/fs/ufs/file.c b/fs/ufs/file.c
index 0e5001512a9d..a9c6e5f04fae 100644
--- a/fs/ufs/file.c
+++ b/fs/ufs/file.c
@@ -60,7 +60,3 @@ const struct file_operations ufs_file_operations = {
         .fsync          = ufs_sync_file,
         .sendfile       = generic_file_sendfile,
 };
-
-struct inode_operations ufs_file_inode_operations = {
-        .truncate       = ufs_truncate,
-};
diff --git a/fs/ufs/inode.c b/fs/ufs/inode.c
index 488b5ff48afb..e7c8615beb65 100644
--- a/fs/ufs/inode.c
+++ b/fs/ufs/inode.c
@@ -843,14 +843,17 @@ int ufs_sync_inode (struct inode *inode)
 
 void ufs_delete_inode (struct inode * inode)
 {
+        loff_t old_i_size;
+
         truncate_inode_pages(&inode->i_data, 0);
         /*UFS_I(inode)->i_dtime = CURRENT_TIME;*/
         lock_kernel();
         mark_inode_dirty(inode);
         ufs_update_inode(inode, IS_SYNC(inode));
+        old_i_size = inode->i_size;
         inode->i_size = 0;
-        if (inode->i_blocks)
-                ufs_truncate (inode);
+        if (inode->i_blocks && ufs_truncate(inode, old_i_size))
+                ufs_warning(inode->i_sb, __FUNCTION__, "ufs_truncate failed\n");
         ufs_free_inode (inode);
         unlock_kernel();
 }
diff --git a/fs/ufs/truncate.c b/fs/ufs/truncate.c
index 3c3b301f8701..c9b55872079b 100644
--- a/fs/ufs/truncate.c
+++ b/fs/ufs/truncate.c
@@ -369,24 +369,97 @@ static int ufs_trunc_tindirect (struct inode * inode)
         UFSD("EXIT\n");
         return retry;
 }
-                
-void ufs_truncate (struct inode * inode)
+
+static int ufs_alloc_lastblock(struct inode *inode)
 {
+        int err = 0;
+        struct address_space *mapping = inode->i_mapping;
+        struct ufs_sb_private_info *uspi = UFS_SB(inode->i_sb)->s_uspi;
         struct ufs_inode_info *ufsi = UFS_I(inode);
-        struct super_block * sb;
-        struct ufs_sb_private_info * uspi;
-        int retry;
+        unsigned lastfrag, i, end;
+        struct page *lastpage;
+        struct buffer_head *bh;
+
+        lastfrag = (i_size_read(inode) + uspi->s_fsize - 1) >> uspi->s_fshift;
+
+        if (!lastfrag) {
+                ufsi->i_lastfrag = 0;
+                goto out;
+        }
+        lastfrag--;
+
+        lastpage = ufs_get_locked_page(mapping, lastfrag >>
+                                       (PAGE_CACHE_SHIFT - inode->i_blkbits));
+       if (IS_ERR(lastpage)) {
+               err = -EIO;
+               goto out;
+       }
+
+       end = lastfrag & ((1 << (PAGE_CACHE_SHIFT - inode->i_blkbits)) - 1);
+       bh = page_buffers(lastpage);
+       for (i = 0; i < end; ++i)
+               bh = bh->b_this_page;
+
+       if (!buffer_mapped(bh)) {
+               err = ufs_getfrag_block(inode, lastfrag, bh, 1);
+
+               if (unlikely(err))
+                       goto out_unlock;
+
+               if (buffer_new(bh)) {
+                       clear_buffer_new(bh);
+                       unmap_underlying_metadata(bh->b_bdev,
+                                                 bh->b_blocknr);
+                       /*
+                        * we do not zeroize fragment, because of
+                        * if it maped to hole, it already contains zeroes
+                        */
+                       set_buffer_uptodate(bh);
+                       mark_buffer_dirty(bh);
+                       set_page_dirty(lastpage);
+               }
+       }
+out_unlock:
+       ufs_put_locked_page(lastpage);
+out:
+       return err;
+}
+
+int ufs_truncate(struct inode *inode, loff_t old_i_size)
+{
+        struct ufs_inode_info *ufsi = UFS_I(inode);
+        struct super_block *sb = inode->i_sb;
+        struct ufs_sb_private_info *uspi = UFS_SB(sb)->s_uspi;
+        int retry, err = 0;
         
         UFSD("ENTER\n");
-        sb = inode->i_sb;
-        uspi = UFS_SB(sb)->s_uspi;
 
-        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)))
-                return;
+        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+              S_ISLNK(inode->i_mode)))
+                return -EINVAL;
         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-                return;
+                return -EPERM;
+
+        if (inode->i_size > old_i_size) {
+                /*
+                 * if we expand file we should care about
+                 * allocation of block for last byte first of all
+                 */
+                err = ufs_alloc_lastblock(inode);
+
+                if (err) {
+                        i_size_write(inode, old_i_size);
+                        goto out;
+                }
+                /*
+                 * go away, because of we expand file, and we do not
+                 * need free blocks, and zeroizes page
+                 */
+                lock_kernel();
+                goto almost_end;
+        }
 
-        block_truncate_page(inode->i_mapping,   inode->i_size, ufs_getfrag_block);
+        block_truncate_page(inode->i_mapping, inode->i_size, ufs_getfrag_block);
 
         lock_kernel();
         while (1) {
@@ -404,9 +477,58 @@ void ufs_truncate (struct inode * inode)
                 yield();
         }
 
+        if (inode->i_size < old_i_size) {
+                /*
+                 * now we should have enough space
+                 * to allocate block for last byte
+                 */
+                err = ufs_alloc_lastblock(inode);
+                if (err)
+                        /*
+                         * looks like all the same - we have no space,
+                         * but we truncate file already
+                         */
+                        inode->i_size = (ufsi->i_lastfrag - 1) * uspi->s_fsize;
+        }
+almost_end:
         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
-        ufsi->i_lastfrag = DIRECT_FRAGMENT;
         unlock_kernel();
         mark_inode_dirty(inode);
-        UFSD("EXIT\n");
+out:
+        UFSD("EXIT: err %d\n", err);
+        return err;
 }
+
+
+/*
+ * We don't define our `inode->i_op->truncate', and call it here,
+ * because of:
+ * - there is no way to know old size
+ * - there is no way inform user about error, if it happens in `truncate'
+ */
+static int ufs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        struct inode *inode = dentry->d_inode;
+        unsigned int ia_valid = attr->ia_valid;
+        int error;
+
+        error = inode_change_ok(inode, attr);
+        if (error)
+                return error;
+
+        if (ia_valid & ATTR_SIZE &&
+            attr->ia_size != i_size_read(inode)) {
+                loff_t old_i_size = inode->i_size;
+                error = vmtruncate(inode, attr->ia_size);
+                if (error)
+                        return error;
+                error = ufs_truncate(inode, old_i_size);
+                if (error)
+                        return error;
+        }
+        return inode_setattr(inode, attr);
+}
+
+struct inode_operations ufs_file_inode_operations = {
+        .setattr = ufs_setattr,
+};
diff --git a/fs/ufs/util.c b/fs/ufs/util.c
index a2f13f45708b..337cf2c46d10 100644
--- a/fs/ufs/util.c
+++ b/fs/ufs/util.c
@@ -233,3 +233,57 @@ ufs_set_inode_dev(struct super_block *sb, struct ufs_inode_info *ufsi, dev_t dev
         else
                 ufsi->i_u1.i_data[0] = fs32;
 }
+
+/**
+ * ufs_get_locked_page() - locate, pin and lock a pagecache page, if not exist
+ * read it from disk.
+ * @mapping: the address_space to search
+ * @index: the page index
+ *
+ * Locates the desired pagecache page, if not exist we'll read it,
+ * locks it, increments its reference
+ * count and returns its address.
+ *
+ */
+
+struct page *ufs_get_locked_page(struct address_space *mapping,
+                                 pgoff_t index)
+{
+        struct page *page;
+
+try_again:
+        page = find_lock_page(mapping, index);
+        if (!page) {
+                page = read_cache_page(mapping, index,
+                                       (filler_t*)mapping->a_ops->readpage,
+                                       NULL);
+                if (IS_ERR(page)) {
+                        printk(KERN_ERR "ufs_change_blocknr: "
+                               "read_cache_page error: ino %lu, index: %lu\n",
+                               mapping->host->i_ino, index);
+                        goto out;
+                }
+
+                lock_page(page);
+
+                if (!PageUptodate(page) || PageError(page)) {
+                        unlock_page(page);
+                        page_cache_release(page);
+
+                        printk(KERN_ERR "ufs_change_blocknr: "
+                               "can not read page: ino %lu, index: %lu\n",
+                               mapping->host->i_ino, index);
+
+                        page = ERR_PTR(-EIO);
+                        goto out;
+                }
+        }
+
+        if (unlikely(!page->mapping || !page_has_buffers(page))) {
+                unlock_page(page);
+                page_cache_release(page);
+                goto try_again;/*we really need these buffers*/
+        }
+out:
+        return page;
+}
diff --git a/fs/ufs/util.h b/fs/ufs/util.h
index 406981fff5e7..28fce6c239b5 100644
--- a/fs/ufs/util.h
+++ b/fs/ufs/util.h
@@ -251,6 +251,14 @@ extern void _ubh_ubhcpymem_(struct ufs_sb_private_info *, unsigned char *, struc
 #define ubh_memcpyubh(ubh,mem,size) _ubh_memcpyubh_(uspi,ubh,mem,size)
 extern void _ubh_memcpyubh_(struct ufs_sb_private_info *, struct ufs_buffer_head *, unsigned char *, unsigned);
 
+/* This functions works with cache pages*/
+extern struct page *ufs_get_locked_page(struct address_space *mapping,
+                                        pgoff_t index);
+static inline void ufs_put_locked_page(struct page *page)
+{
+       unlock_page(page);
+       page_cache_release(page);
+}
 
 
 /*