Merge branch 'for-6.15/intel-ish' into for-linus

- intel-ish Kbuild cleanup (Jiri Kosina)

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 36f51c311bb1..0b568c8d24cb 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1039,7 +1039,6 @@ int btrfs_write_check(struct kiocb *iocb, size_t count)
 	loff_t pos = iocb->ki_pos;
 	int ret;
 	loff_t oldsize;
-	loff_t start_pos;
 
 	/*
 	 * Quickly bail out on NOWAIT writes if we don't have the nodatacow or
@@ -1066,9 +1065,8 @@ int btrfs_write_check(struct kiocb *iocb, size_t count)
 		inode_inc_iversion(inode);
 	}
 
-	start_pos = round_down(pos, fs_info->sectorsize);
 	oldsize = i_size_read(inode);
-	if (start_pos > oldsize) {
+	if (pos > oldsize) {
 		/* Expand hole size to cover write data, preventing empty gap */
 		loff_t end_pos = round_up(pos + count, fs_info->sectorsize);
 
@@ -1092,7 +1090,7 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i)
 	u64 lockend;
 	size_t num_written = 0;
 	ssize_t ret;
-	loff_t old_isize = i_size_read(inode);
+	loff_t old_isize;
 	unsigned int ilock_flags = 0;
 	const bool nowait = (iocb->ki_flags & IOCB_NOWAIT);
 	unsigned int bdp_flags = (nowait ? BDP_ASYNC : 0);
@@ -1105,6 +1103,13 @@ ssize_t btrfs_buffered_write(struct kiocb *iocb, struct iov_iter *i)
 	if (ret < 0)
 		return ret;
 
+	/*
+	 * We can only trust the isize with inode lock held, or it can race with
+	 * other buffered writes and cause incorrect call of
+	 * pagecache_isize_extended() to overwrite existing data.
+	 */
+	old_isize = i_size_read(inode);
+
 	ret = generic_write_checks(iocb, i);
 	if (ret <= 0)
 		goto out;