From bcf0b7f18ad11e1d410e82ffef678705eff0a317 Mon Sep 17 00:00:00 2001 From: Daejun Park Date: Thu, 29 Oct 2026 11:23:00 +0900 Subject: [PATCH] xfs: refuse a pNFS LAYOUTCOMMIT of a range without blocks A client can commit a hole in a LAYOUTCOMMIT, because nfsd does not check the extents against its layouts. xfs_iomap_write_unwritten() then allocates written blocks there. A large hole overruns the block reservation and shuts XFS down. A small one exposes stale data. Refuse such a range with -EIO, using XFS_BMAPI_CONVERT_ONLY. Link: https://lore.kernel.org/r/20261014130834.GB15773@lst.de Fixes: 527851124d10 ("xfs: implement pNFS export operations") Cc: stable@vger.kernel.org Signed-off-by: Daejun Park Reviewed-by: Christoph Hellwig Signed-off-by: Carlos Maiolino --- fs/xfs/xfs_file.c | 2 +- fs/xfs/xfs_ioend.c | 2 +- fs/xfs/xfs_iomap.c | 20 +++++++++++++++++--- fs/xfs/xfs_iomap.h | 3 ++- fs/xfs/xfs_pnfs.c | 9 ++++++++- 5 files changed, 29 insertions(+), 7 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 1eab6dbb4c5f..d2a2124bff54 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -666,7 +666,7 @@ xfs_dio_write_end_io( * they are converted. */ if (flags & IOMAP_DIO_UNWRITTEN) { - error = xfs_iomap_write_unwritten(ip, offset, size, true); + error = xfs_iomap_write_unwritten(ip, offset, size, true, 0); goto out; } diff --git a/fs/xfs/xfs_ioend.c b/fs/xfs/xfs_ioend.c index 48becc3bf608..7f4a4a95afe5 100644 --- a/fs/xfs/xfs_ioend.c +++ b/fs/xfs/xfs_ioend.c @@ -237,7 +237,7 @@ xfs_end_ioend_write( if (ioend->io_flags & IOMAP_IOEND_SHARED) error = xfs_reflink_end_cow(ip, offset, size); else if (ioend->io_flags & IOMAP_IOEND_UNWRITTEN) - error = xfs_iomap_write_unwritten(ip, offset, size, false); + error = xfs_iomap_write_unwritten(ip, offset, size, false, 0); if (!error && !(ioend->io_flags & IOMAP_IOEND_DIRECT) && diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 329c745e3120..99d48081c5ac 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -614,7 +614,8 @@ xfs_iomap_write_unwritten( xfs_inode_t *ip, xfs_off_t offset, xfs_off_t count, - bool update_isize) + bool update_isize, + uint32_t bmapi_flags) { xfs_mount_t *mp = ip->i_mount; xfs_fileoff_t offset_fsb; @@ -676,8 +677,21 @@ xfs_iomap_write_unwritten( */ nimaps = 1; error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, - XFS_BMAPI_CONVERT, resblks, &imap, - &nimaps); + XFS_BMAPI_CONVERT | bmapi_flags, + resblks, &imap, &nimaps); + if (error == -ENOSR && (bmapi_flags & XFS_BMAPI_CONVERT_ONLY)) { + /* + * Nothing was mapped: the rest of the range starts + * with a hole or a delalloc extent. Nothing was + * changed either, but xfs_iext_count_extend() may + * have logged the inode, and cancelling a dirty + * transaction shuts the filesystem down. Commit it, + * as xfs_alloc_file_space() does on -ENOSR. + */ + error = xfs_trans_commit(tp); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error ? error : -EIO; + } if (error) goto error_on_bmapi_transaction; diff --git a/fs/xfs/xfs_iomap.h b/fs/xfs/xfs_iomap.h index f2520a9b3a13..8fc0c6fc8bea 100644 --- a/fs/xfs/xfs_iomap.h +++ b/fs/xfs/xfs_iomap.h @@ -15,7 +15,8 @@ struct xfs_zone_alloc_ctx; int xfs_iomap_write_direct(struct xfs_inode *ip, xfs_fileoff_t offset_fsb, xfs_fileoff_t count_fsb, unsigned int flags, struct xfs_bmbt_irec *imap, u64 *sequence); -int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, xfs_off_t, bool); +int xfs_iomap_write_unwritten(struct xfs_inode *ip, xfs_off_t offset, + xfs_off_t count, bool update_isize, uint32_t bmapi_flags); xfs_fileoff_t xfs_iomap_eof_align_last_fsb(struct xfs_inode *ip, xfs_fileoff_t end_fsb); diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c index a9f0b472f307..7ff83274a513 100644 --- a/fs/xfs/xfs_pnfs.c +++ b/fs/xfs/xfs_pnfs.c @@ -344,7 +344,14 @@ xfs_fs_commit_blocks( (end - 1) >> PAGE_SHIFT); WARN_ON_ONCE(error); - error = xfs_iomap_write_unwritten(ip, start, length, false); + /* + * A client may only write to blocks that a layout handed out, + * and xfs_fs_map_blocks() allocates blocks for any hole in a + * write layout, so refuse to allocate blocks for a hole or a + * delalloc extent in the committed range. + */ + error = xfs_iomap_write_unwritten(ip, start, length, false, + XFS_BMAPI_CONVERT_ONLY); if (error) goto out_drop_iolock; }