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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 v5] f2fs: prevent writing without fallocate() for pinned files
Date: Tue, 26 Mar 2024 13:31:30 -0700
Message-ID: <20240326203130.85748-1-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
---
 fs/f2fs/data.c | 20 ++++++++++++++++----
 fs/f2fs/file.c | 18 +++++++++---------
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index c21b92f18463..1b02a9291176 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) &&
+		     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..7aa53cf553a1 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;
@@ -3235,7 +3231,7 @@ 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;
 	}
@@ -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