From c9b1194e8ec99d95db25db45edd2fbf690f043ab Mon Sep 17 00:00:00 2001 From: Paulo Alcantara Date: Sat, 26 Sep 2026 13:04:44 -0300 Subject: smb: client: drain and invalidate before server-side copy/clone cifs_file_copychunk_range() and the clone (FICLONE) path of cifs_remap_file_range() do not serialise the destination page cache against the server-side copy the way the other server-side range operations (smb3_zero_range(), smb3_punch_hole(), smb3_collapse_range() and smb3_insert_range()) do. cifs_file_copychunk_range() invalidates the destination range with filemap_invalidate_inode(), which takes and drops the mapping's invalidate_lock internally, so the lock is no longer held when the copychunk ioctl is issued. It also never drains in-flight netfs I/O on the target. The clone path never takes the invalidate_lock at all (only i_rwsem), uses a bare truncate_inode_pages_range() and likewise does not drain outstanding I/O. As a result an asynchronous destination writeback can complete after the server-side copy/clone has run and reinstate stale data over the region just written by the server, corrupting the file. This is the same class of corruption as commit d7d2adcd022b ("smb/client: flush dirty data before punching a hole") and has been seen randomly in generic/363 against Windows Server. Fix both paths to follow the established ordering: hold the target mapping's invalidate_lock across the flush and invalidation of the destination and the server ioctl, and call netfs_wait_for_outstanding_io() on the target to drain in-flight writes before the ioctl is issued. Only the target inode's invalidate_lock is required, as the source is merely flushed and not invalidated; i_rwsem (already held via lock_two_nondirectories()) is acquired before the invalidate_lock, matching the VFS lock ordering. Since filemap_invalidate_inode() takes that same lock internally, replace it with its own unmap/flush/invalidate steps instead of calling it, and return early on a zero-length copy to avoid a range underflow. Fixes: 8101d6e112e2 ("cifs: Fix copy offload to flush destination region") Fixes: c54fc3a4f375 ("cifs: Fix flushing, invalidation and file size with FICLONE") Reviewed-by: David Howells Reviewed-by: Namjae Jeon Signed-off-by: Paulo Alcantara Cc: Christian Brauner Cc: Matthew Wilcox Cc: Ronnie Sahlberg Cc: Shyam Prasad N Cc: Tom Talpey Cc: Bharath SM Cc: stable@vger.kernel.org --- fs/smb/client/cifsfs.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-) (limited to 'fs') diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c index 6410249f529a..98b610b2a114 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -1412,6 +1412,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, * server could even support copy of range where source = target */ lock_two_nondirectories(target_inode, src_inode); + filemap_invalidate_lock(target_inode->i_mapping); if (len == 0) { loff_t src_size = i_size_read(src_inode); @@ -1475,6 +1476,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, cifs_dbg(FYI, "about to discard pages %llx-%llx\n", fstart, fend); truncate_inode_pages_range(&target_inode->i_data, min(fstart, i_size), fend); + netfs_wait_for_outstanding_io(target_inode); fscache_invalidate(cifs_inode_cookie(target_inode), NULL, i_size, 0); @@ -1513,6 +1515,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, if (rc) CIFS_I(target_inode)->time = 0; unlock: + filemap_invalidate_unlock(target_inode->i_mapping); /* although unlocking in the reverse order from locking is not strictly necessary here it is a little cleaner to be consistent */ unlock_two_nondirectories(src_inode, target_inode); @@ -1536,6 +1539,9 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, struct cifs_tcon *target_tcon; ssize_t rc; + if (len == 0) + return 0; + cifs_dbg(FYI, "copychunk range\n"); if (!src_file->private_data || !dst_file->private_data) { @@ -1565,6 +1571,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, * server could even support copy of range where source = target */ lock_two_nondirectories(target_inode, src_inode); + filemap_invalidate_lock(target_inode->i_mapping); cifs_dbg(FYI, "about to flush pages\n"); @@ -1590,11 +1597,24 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, * Start at the old EOF when extending so the folio straddling it, which * may hold data written past EOF through an mmap, is dropped too. */ - rc = filemap_invalidate_inode(target_inode, true, - min(destoff, i_size_read(target_inode)), - destoff + len - 1); - if (rc) - goto unlock; + if (target_inode->i_mapping->nrpages) { + loff_t fstart = min(destoff, i_size_read(target_inode)); + loff_t fend = destoff + len - 1; + + unmap_mapping_pages(target_inode->i_mapping, + fstart >> PAGE_SHIFT, + (fend >> PAGE_SHIFT) - + (fstart >> PAGE_SHIFT) + 1, + false); + rc = filemap_write_and_wait_range(target_inode->i_mapping, + fstart, fend); + if (rc) + goto unlock; + invalidate_inode_pages2_range(target_inode->i_mapping, + fstart >> PAGE_SHIFT, + fend >> PAGE_SHIFT); + } + netfs_wait_for_outstanding_io(target_inode); fscache_invalidate(cifs_inode_cookie(target_inode), NULL, i_size_read(target_inode), 0); @@ -1626,6 +1646,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, CIFS_I(target_inode)->time = 0; unlock: + filemap_invalidate_unlock(target_inode->i_mapping); /* although unlocking in the reverse order from locking is not * strictly necessary here it is a little cleaner to be consistent */ -- cgit v1.2.3