linux-kernel - [PATCH v3] f2fs: prevent writing without fallocate() for pinned files

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Date: Tue, 19 Mar 2024 14:23:16 -0700
From: Daeho Jeong <daeho43@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	kernel-team@...roid.com
Cc: Daeho Jeong <daehojeong@...gle.com>
Subject: [PATCH v3] f2fs: prevent writing without fallocate() for pinned files

From: Daeho Jeong <daehojeong@...gle.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@...gle.com>
---
v2: covered the direct io case
v3: covered the mkwrite case
---
 fs/f2fs/data.c | 14 ++++++++++++--
 fs/f2fs/file.c | 16 ++++++++--------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c21b92f18463..d3e5ab2736a6 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;
 	}
@@ -3407,6 +3412,11 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
 
 	if (!f2fs_lookup_read_extent_cache_block(inode, index,
 						 &dn.data_blkaddr)) {
+		if (f2fs_is_pinned_file(inode)) {
+			err = -EIO;
+			goto out;
+		}
+
 		if (locked) {
 			err = f2fs_reserve_block(&dn, index);
 			goto out;
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);
-- 
2.44.0.291.gc1ea87d7ee-goog