[PATCH v4] xfs: Check for delayed allocations before setting extsize

[Ojaswin Mujoo]

Extsize should only be allowed to be set on files with no data in it.
For this, we check if the files have extents but miss to check if
delayed extents are present. This patch adds that check.

While we are at it, also refactor this check into a helper since
it's used in some other places as well like xfs_inactive() or
xfs_ioctl_setattr_xflags()

**Without the patch (SUCCEEDS)**

$ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'

wrote 1024/1024 bytes at offset 0
1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)

**With the patch (FAILS as expected)**

$ xfs_io -c 'open -f testfile' -c 'pwrite 0 1024' -c 'extsize 65536'

wrote 1024/1024 bytes at offset 0
1 KiB, 1 ops; 0.0002 sec (4.628 MiB/sec and 4739.3365 ops/sec)
xfs_io: FS_IOC_FSSETXATTR testfile: Invalid argument

Fixes: e94af02a9cd7 ("[XFS] fix old xfs_setattr mis-merge from irix; mostly harmless esp if not using xfs rt")
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>
Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
---

Changes since v3:

* Add Fixes tags
* Minor rewording of commit message 

v3:
https://lore.kernel.org/linux-xfs/20241011145427.266614-1-ojaswin@xxxxxxxxxxxxx/

 fs/xfs/xfs_inode.c | 2 +-
 fs/xfs/xfs_inode.h | 5 +++++
 fs/xfs/xfs_ioctl.c | 4 ++--
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index bcc277fc0a83..19dcb569a3e7 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1409,7 +1409,7 @@ xfs_inactive(
 
 	if (S_ISREG(VFS_I(ip)->i_mode) &&
 	    (ip->i_disk_size != 0 || XFS_ISIZE(ip) != 0 ||
-	     ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0))
+	     xfs_inode_has_filedata(ip)))
 		truncate = 1;
 
 	if (xfs_iflags_test(ip, XFS_IQUOTAUNCHECKED)) {
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 97ed912306fd..03944b6c5fba 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -292,6 +292,11 @@ static inline bool xfs_is_cow_inode(struct xfs_inode *ip)
 	return xfs_is_reflink_inode(ip) || xfs_is_always_cow_inode(ip);
 }
 
+static inline bool xfs_inode_has_filedata(const struct xfs_inode *ip)
+{
+	return ip->i_df.if_nextents > 0 || ip->i_delayed_blks > 0;
+}
+
 /*
  * Check if an inode has any data in the COW fork.  This might be often false
  * even for inodes with the reflink flag when there is no pending COW operation.
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index a20d426ef021..2567fd2a0994 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -481,7 +481,7 @@ xfs_ioctl_setattr_xflags(
 
 	if (rtflag != XFS_IS_REALTIME_INODE(ip)) {
 		/* Can't change realtime flag if any extents are allocated. */
-		if (ip->i_df.if_nextents || ip->i_delayed_blks)
+		if (xfs_inode_has_filedata(ip))
 			return -EINVAL;
 
 		/*
@@ -602,7 +602,7 @@ xfs_ioctl_setattr_check_extsize(
 	if (!fa->fsx_valid)
 		return 0;
 
-	if (S_ISREG(VFS_I(ip)->i_mode) && ip->i_df.if_nextents &&
+	if (S_ISREG(VFS_I(ip)->i_mode) && xfs_inode_has_filedata(ip) &&
 	    XFS_FSB_TO_B(mp, ip->i_extsize) != fa->fsx_extsize)
 		return -EINVAL;
 
-- 
2.43.5