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smb: client: discard post-EOF pagecache when extending a file via zero range

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smb3_zero_range() removed the pagecache only for the range being zeroed,
so when it extends the file the folio straddling the old EOF - which may
hold data dirtied past EOF through an mmap - was never dropped and became
visible as file content once the file was extended.

Lower the discard boundary to the smaller of the zero-range offset and the
old EOF.

Fixes: 72c419d9b0 ("cifs: fix smb3_zero_range so it can expand the file-size when required")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Paulo Alcantara 2026-09-20 16:09:30 -03:00
parent 35024595f6
commit da4fe97fb6
1 changed files with 4 additions and 1 deletions
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5
fs/smb/client/smb2ops.c
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@ -3560,8 +3560,11 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
/*
* We zero the range through ioctl, so we need remove the page caches
* first, otherwise the data may be inconsistent with the server.
*
* 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.
*/
truncate_pagecache_range(inode, offset, offset + len - 1);
truncate_pagecache_range(inode, min(offset, i_size), offset + len - 1);
netfs_wait_for_outstanding_io(inode);
/* if file not oplocked can't be sure whether asking to extend size */