bcachefs: Don't write past eof

When converting from PAGE_SIZE to block_size, the .mkwrite path was
missed

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/fs-io.c b/fs/bcachefs/fs-io.c
index 4a016c19dcbd14aed9c7d92bcc928397f4f1a81f..f05950da6957759eb4b16ed21167fbfdb3c997e0 100644 (file)
--- a/fs/bcachefs/fs-io.c
+++ b/fs/bcachefs/fs-io.c
@@ -801,6 +801,8 @@ vm_fault_t bch2_page_mkwrite(struct vm_fault *vmf)
        struct address_space *mapping = file->f_mapping;
        struct bch_fs *c = inode->v.i_sb->s_fs_info;
        struct bch2_page_reservation res;
+       unsigned len;
+       loff_t isize;
        int ret = VM_FAULT_LOCKED;
 
        bch2_page_reservation_init(c, inode, &res);
@@ -817,21 +819,27 @@ vm_fault_t bch2_page_mkwrite(struct vm_fault *vmf)
        bch2_pagecache_add_get(&inode->ei_pagecache_lock);
 
        lock_page(page);
-       if (page->mapping != mapping ||
-           page_offset(page) > i_size_read(&inode->v)) {
+       isize = i_size_read(&inode->v);
+
+       if (page->mapping != mapping || page_offset(page) >= isize) {
                unlock_page(page);
                ret = VM_FAULT_NOPAGE;
                goto out;
        }
 
-       if (bch2_page_reservation_get(c, inode, page, &res,
-                                     0, PAGE_SIZE, true)) {
+       /* page is wholly or partially inside EOF */
+       if (((page->index + 1) << PAGE_SHIFT) <= isize)
+               len = PAGE_SIZE;
+       else
+               len = offset_in_page(isize);
+
+       if (bch2_page_reservation_get(c, inode, page, &res, 0, len, true)) {
                unlock_page(page);
                ret = VM_FAULT_SIGBUS;
                goto out;
        }
 
-       bch2_set_page_dirty(c, inode, page, &res, 0, PAGE_SIZE);
+       bch2_set_page_dirty(c, inode, page, &res, 0, len);
        wait_for_stable_page(page);
 out:
        bch2_pagecache_add_put(&inode->ei_pagecache_lock);
@@ -1433,6 +1441,10 @@ do_io:
                BUG_ON(!bio_add_page(&w->io->op.op.wbio.bio, page,
                                     sectors << 9, offset << 9));
 
+               /* Check for writing past i_size: */
+               BUG_ON((bio_end_sector(&w->io->op.op.wbio.bio) << 9) >
+                      round_up(i_size, block_bytes(c)));
+
                w->io->op.op.res.sectors += reserved_sectors;
                w->io->op.new_i_size = i_size;
 
@@ -2518,6 +2530,16 @@ int bch2_truncate(struct bch_inode_info *inode, struct iattr *iattr)
        if (unlikely(ret))
                goto err;
 
+       /*
+        * When extending, we're going to write the new i_size to disk
+        * immediately so we need to flush anything above the current on disk
+        * i_size first:
+        *
+        * Also, when extending we need to flush the page that i_size currently
+        * straddles - if it's mapped to userspace, we need to ensure that
+        * userspace has to redirty it and call .mkwrite -> set_page_dirty
+        * again to allocate the part of the page that was extended.
+        */
        if (iattr->ia_size > inode->ei_inode.bi_size)
                ret = filemap_write_and_wait_range(mapping,
                                inode->ei_inode.bi_size,