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From: Daeho Jeong <daeho43@gmail.com>
To: linux-kernel@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	kernel-team@android.com
Cc: Daeho Jeong <daehojeong@google.com>
Subject: [PATCH 1/2] f2fs: prevent writing without fallocate() for pinned files
Date: Thu, 11 Apr 2024 10:54:10 -0700
Message-ID: <20240411175410.2406710-1-daeho43@gmail.com>
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From: Daeho Jeong <daehojeong@google.com>

In a case writing without fallocate(), we can't guarantee it's allocated
in the conventional area for zoned stroage. To make it consistent across
storage devices, we disallow it regardless of storage device types.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
v2: covered the direct io case
v3: covered the mkwrite case
v4: moved pin file check position in prepare_write_begin()
v5: removed unnecessary condition in f2fs_map_blocks() and disallowed
    pre-written inodes for file pinning
v6: check a hole for pinned files in mkwrite()
v7: changed data_blkaddr check condition in mkwrite()
v8: replaced overwrite check parts with f2fs_overwrite_io()
---
 fs/f2fs/file.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 1761ad125f97..3ee61bc82c6f 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -58,7 +58,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
 	struct inode *inode = file_inode(vmf->vma->vm_file);
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct dnode_of_data dn;
-	bool need_alloc = true;
+	bool need_alloc = !f2fs_is_pinned_file(inode);
 	int err = 0;
 	vm_fault_t ret;
 
@@ -115,19 +115,18 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf)
 		goto out_sem;
 	}
 
+	set_new_dnode(&dn, inode, NULL, NULL, 0);
 	if (need_alloc) {
 		/* block allocation */
-		set_new_dnode(&dn, inode, NULL, NULL, 0);
 		err = f2fs_get_block_locked(&dn, page->index);
-	}
-
-#ifdef CONFIG_F2FS_FS_COMPRESSION
-	if (!need_alloc) {
-		set_new_dnode(&dn, inode, NULL, NULL, 0);
+	} else {
 		err = f2fs_get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
 		f2fs_put_dnode(&dn);
+		if (f2fs_is_pinned_file(inode) &&
+		    !__is_valid_data_blkaddr(dn.data_blkaddr))
+			err = -EIO;
 	}
-#endif
+
 	if (err) {
 		unlock_page(page);
 		goto out_sem;
@@ -3234,7 +3233,7 @@ static int f2fs_ioc_set_pin_file(struct file *filp, unsigned long arg)
 		goto done;
 	}
 
-	if (f2fs_sb_has_blkzoned(sbi) && F2FS_HAS_BLOCKS(inode)) {
+	if (F2FS_HAS_BLOCKS(inode)) {
 		ret = -EFBIG;
 		goto out;
 	}
@@ -4798,6 +4797,8 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	bool dio;
 	bool may_need_sync = true;
 	int preallocated;
+	const loff_t pos = iocb->ki_pos;
+	const ssize_t count = iov_iter_count(from);
 	ssize_t ret;
 
 	if (unlikely(f2fs_cp_error(F2FS_I_SB(inode)))) {
@@ -4819,6 +4820,12 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		inode_lock(inode);
 	}
 
+	if (f2fs_is_pinned_file(inode) &&
+	    !f2fs_overwrite_io(inode, pos, count)) {
+		ret = -EIO;
+		goto out_unlock;
+	}
+
 	ret = f2fs_write_checks(iocb, from);
 	if (ret <= 0)
 		goto out_unlock;
-- 
2.44.0.683.g7961c838ac-goog