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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 v4] f2fs: prevent writing without fallocate() for pinned files
Date: Fri, 22 Mar 2024 10:49:43 -0700
Message-ID: <20240322174944.1460441-1-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.

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()
---
 fs/f2fs/data.c | 20 ++++++++++++++++----
 fs/f2fs/file.c | 16 ++++++++--------
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c21b92f18463..88896989bb28 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1584,8 +1584,11 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 
 	/* use out-place-update for direct IO under LFS mode */
 	if (map->m_may_create &&
-	    (is_hole || (f2fs_lfs_mode(sbi) && flag == F2FS_GET_BLOCK_DIO))) {
-		if (unlikely(f2fs_cp_error(sbi))) {
+	    (is_hole || (f2fs_lfs_mode(sbi) && flag == F2FS_GET_BLOCK_DIO &&
+			 !f2fs_is_pinned_file(inode)))) {
+		if (unlikely(f2fs_cp_error(sbi)) ||
+		    (f2fs_is_pinned_file(inode) && is_hole &&
+		     flag != F2FS_GET_BLOCK_PRE_DIO)) {
 			err = -EIO;
 			goto sync_out;
 		}
@@ -3378,6 +3381,8 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
 		f2fs_map_lock(sbi, flag);
 		locked = true;
 	} else if ((pos & PAGE_MASK) >= i_size_read(inode)) {
+		if (f2fs_is_pinned_file(inode))
+			return -EIO;
 		f2fs_map_lock(sbi, flag);
 		locked = true;
 	}
@@ -3414,8 +3419,15 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
 
 		/* hole case */
 		err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
-		if (!err && dn.data_blkaddr != NULL_ADDR)
-			goto out;
+		if (!err) {
+			if (dn.data_blkaddr != NULL_ADDR) {
+				goto out;
+			} else if (f2fs_is_pinned_file(inode)) {
+				err = -EIO;
+				goto out;
+			}
+		}
+
 		f2fs_put_dnode(&dn);
 		f2fs_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO);
 		WARN_ON(flag != F2FS_GET_BLOCK_PRE_AIO);
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 82277e95c88f..4db3b21c804b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -57,7 +57,7 @@ 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;
 
@@ -114,19 +114,15 @@ 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);
 	}
-#endif
+
 	if (err) {
 		unlock_page(page);
 		goto out_sem;
@@ -4611,6 +4607,10 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
 			return ret;
 	}
 
+	/* For pinned files, it should be fallocate()-ed in advance. */
+	if (f2fs_is_pinned_file(inode))
+		return 0;
+
 	/* Do not preallocate blocks that will be written partially in 4KB. */
 	map.m_lblk = F2FS_BLK_ALIGN(pos);
 	map.m_len = F2FS_BYTES_TO_BLK(pos + count);
-- 
2.44.0.396.g6e790dbe36-goog