ext2: convert to use the new truncate convention.

I also have commented a possible bug in existing ext2 code, marked with XXX.

Cc: linux-ext4@vger.kernel.org
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 119 insertions, 36 deletions

diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 8e917b686510..52b34f1d2738 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -122,7 +122,6 @@ extern int ext2_write_inode (struct inode *, struct writeback_control *);
 extern void ext2_delete_inode (struct inode *);
 extern int ext2_sync_inode (struct inode *);
 extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
-extern void ext2_truncate (struct inode *);
 extern int ext2_setattr (struct dentry *, struct iattr *);
 extern void ext2_set_inode_flags(struct inode *inode);
 extern void ext2_get_inode_flags(struct ext2_inode_info *);
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index d82e7ca93455..49eec9456c5b 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -95,7 +95,6 @@ const struct file_operations ext2_xip_file_operations = {
 #endif
 
 const struct inode_operations ext2_file_inode_operations = {
-        .truncate       = ext2_truncate,
 #ifdef CONFIG_EXT2_FS_XATTR
         .setxattr       = generic_setxattr,
         .getxattr       = generic_getxattr,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 527c46d9bc1f..19214435b752 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -54,6 +54,18 @@ static inline int ext2_inode_is_fast_symlink(struct inode *inode)
                 inode->i_blocks - ea_blocks == 0);
 }
 
+static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
+
+static void ext2_write_failed(struct address_space *mapping, loff_t to)
+{
+        struct inode *inode = mapping->host;
+
+        if (to > inode->i_size) {
+                truncate_pagecache(inode, to, inode->i_size);
+                ext2_truncate_blocks(inode, inode->i_size);
+        }
+}
+
 /*
  * Called at the last iput() if i_nlink is zero.
  */
@@ -71,7 +83,7 @@ void ext2_delete_inode (struct inode * inode)
 
         inode->i_size = 0;
         if (inode->i_blocks)
-                ext2_truncate (inode);
+                ext2_truncate_blocks(inode, 0);
         ext2_free_inode (inode);
 
         return;
@@ -757,8 +769,8 @@ int __ext2_write_begin(struct file *file, struct address_space *mapping,
                 loff_t pos, unsigned len, unsigned flags,
                 struct page **pagep, void **fsdata)
 {
-        return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-                                                        ext2_get_block);
+        return block_write_begin_newtrunc(file, mapping, pos, len, flags,
+                                        pagep, fsdata, ext2_get_block);
 }
 
 static int
@@ -766,8 +778,25 @@ ext2_write_begin(struct file *file, struct address_space *mapping,
                 loff_t pos, unsigned len, unsigned flags,
                 struct page **pagep, void **fsdata)
 {
+        int ret;
+
         *pagep = NULL;
-        return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
+        ret = __ext2_write_begin(file, mapping, pos, len, flags, pagep, fsdata);
+        if (ret < 0)
+                ext2_write_failed(mapping, pos + len);
+        return ret;
+}
+
+static int ext2_write_end(struct file *file, struct address_space *mapping,
+                        loff_t pos, unsigned len, unsigned copied,
+                        struct page *page, void *fsdata)
+{
+        int ret;
+
+        ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
+        if (ret < len)
+                ext2_write_failed(mapping, pos + len);
+        return ret;
 }
 
 static int
@@ -775,13 +804,18 @@ ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
                 loff_t pos, unsigned len, unsigned flags,
                 struct page **pagep, void **fsdata)
 {
+        int ret;
+
         /*
          * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
          * directory handling code to pass around offsets rather than struct
          * pages in order to make this work easily.
          */
-        return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
-                                                        ext2_get_block);
+        ret = nobh_write_begin_newtrunc(file, mapping, pos, len, flags, pagep,
+                                                fsdata, ext2_get_block);
+        if (ret < 0)
+                ext2_write_failed(mapping, pos + len);
+        return ret;
 }
 
 static int ext2_nobh_writepage(struct page *page,
@@ -800,10 +834,15 @@ ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
                         loff_t offset, unsigned long nr_segs)
 {
         struct file *file = iocb->ki_filp;
-        struct inode *inode = file->f_mapping->host;
-
-        return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
-                                offset, nr_segs, ext2_get_block, NULL);
+        struct address_space *mapping = file->f_mapping;
+        struct inode *inode = mapping->host;
+        ssize_t ret;
+
+        ret = blockdev_direct_IO_newtrunc(rw, iocb, inode, inode->i_sb->s_bdev,
+                                iov, offset, nr_segs, ext2_get_block, NULL);
+        if (ret < 0 && (rw & WRITE))
+                ext2_write_failed(mapping, offset + iov_length(iov, nr_segs));
+        return ret;
 }
 
 static int
@@ -818,7 +857,7 @@ const struct address_space_operations ext2_aops = {
         .writepage              = ext2_writepage,
         .sync_page              = block_sync_page,
         .write_begin            = ext2_write_begin,
-        .write_end              = generic_write_end,
+        .write_end              = ext2_write_end,
         .bmap                   = ext2_bmap,
         .direct_IO              = ext2_direct_IO,
         .writepages             = ext2_writepages,
@@ -1027,7 +1066,7 @@ static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int de
                 ext2_free_data(inode, p, q);
 }
 
-void ext2_truncate(struct inode *inode)
+static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
 {
         __le32 *i_data = EXT2_I(inode)->i_data;
         struct ext2_inode_info *ei = EXT2_I(inode);
@@ -1039,27 +1078,8 @@ void ext2_truncate(struct inode *inode)
         int n;
         long iblock;
         unsigned blocksize;
-
-        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
-            S_ISLNK(inode->i_mode)))
-                return;
-        if (ext2_inode_is_fast_symlink(inode))
-                return;
-        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
-                return;
-
         blocksize = inode->i_sb->s_blocksize;
-        iblock = (inode->i_size + blocksize-1)
-                                        >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
-
-        if (mapping_is_xip(inode->i_mapping))
-                xip_truncate_page(inode->i_mapping, inode->i_size);
-        else if (test_opt(inode->i_sb, NOBH))
-                nobh_truncate_page(inode->i_mapping,
-                                inode->i_size, ext2_get_block);
-        else
-                block_truncate_page(inode->i_mapping,
-                                inode->i_size, ext2_get_block);
+        iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
 
         n = ext2_block_to_path(inode, iblock, offsets, NULL);
         if (n == 0)
@@ -1127,6 +1147,62 @@ do_indirects:
         ext2_discard_reservation(inode);
 
         mutex_unlock(&ei->truncate_mutex);
+}
+
+static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
+{
+        /*
+         * XXX: it seems like a bug here that we don't allow
+         * IS_APPEND inode to have blocks-past-i_size trimmed off.
+         * review and fix this.
+         *
+         * Also would be nice to be able to handle IO errors and such,
+         * but that's probably too much to ask.
+         */
+        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+            S_ISLNK(inode->i_mode)))
+                return;
+        if (ext2_inode_is_fast_symlink(inode))
+                return;
+        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+                return;
+        __ext2_truncate_blocks(inode, offset);
+}
+
+int ext2_setsize(struct inode *inode, loff_t newsize)
+{
+        loff_t oldsize;
+        int error;
+
+        error = inode_newsize_ok(inode, newsize);
+        if (error)
+                return error;
+
+        if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+            S_ISLNK(inode->i_mode)))
+                return -EINVAL;
+        if (ext2_inode_is_fast_symlink(inode))
+                return -EINVAL;
+        if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+                return -EPERM;
+
+        if (mapping_is_xip(inode->i_mapping))
+                error = xip_truncate_page(inode->i_mapping, newsize);
+        else if (test_opt(inode->i_sb, NOBH))
+                error = nobh_truncate_page(inode->i_mapping,
+                                newsize, ext2_get_block);
+        else
+                error = block_truncate_page(inode->i_mapping,
+                                newsize, ext2_get_block);
+        if (error)
+                return error;
+
+        oldsize = inode->i_size;
+        i_size_write(inode, newsize);
+        truncate_pagecache(inode, oldsize, newsize);
+
+        __ext2_truncate_blocks(inode, newsize);
+
         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
         if (inode_needs_sync(inode)) {
                 sync_mapping_buffers(inode->i_mapping);
@@ -1134,6 +1210,8 @@ do_indirects:
         } else {
                 mark_inode_dirty(inode);
         }
+
+        return 0;
 }
 
 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
@@ -1474,8 +1552,15 @@ int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
                 if (error)
                         return error;
         }
-        error = inode_setattr(inode, iattr);
-        if (!error && (iattr->ia_valid & ATTR_MODE))
+        if (iattr->ia_valid & ATTR_SIZE) {
+                error = ext2_setsize(inode, iattr->ia_size);
+                if (error)
+                        return error;
+        }
+        generic_setattr(inode, iattr);
+        if (iattr->ia_valid & ATTR_MODE)
                 error = ext2_acl_chmod(inode);
+        mark_inode_dirty(inode);
+
         return error;
 }