Files
David HowellsandChristian Brauner 2c8f4742bb netfs: Fix potential for tearing in ->remote_i_size and ->zero_point
Fix potential tearing in using ->remote_i_size and ->zero_point by copying
i_size_read() and i_size_write() and using the same seqcount as for i_size.

We need to make sure that netfslib and the filesystems that use it always
hold i_lock whilst updating any of the sizes to prevent i_size_seqcount
from getting corrupted.

Fixes: 4058f74210 ("netfs: Keep track of the actual remote file size")
Fixes: 100ccd18bb ("netfs: Optimise away reads above the point at which there can be no data")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-6-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2026-05-12 14:42:30 +02:00

79 lines
2.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* V9FS VFS extensions.
*
* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
*/
#ifndef FS_9P_V9FS_VFS_H
#define FS_9P_V9FS_VFS_H
/* plan9 semantics are that created files are implicitly opened.
* But linux semantics are that you call create, then open.
* the plan9 approach is superior as it provides an atomic
* open.
* we track the create fid here. When the file is opened, if fidopen is
* non-zero, we use the fid and can skip some steps.
* there may be a better way to do this, but I don't know it.
* one BAD way is to clunk the fid on create, then open it again:
* you lose the atomicity of file open
*/
/* special case:
* unlink calls remove, which is an implicit clunk. So we have to track
* that kind of thing so that we don't try to clunk a dead fid.
*/
#define P9_LOCK_TIMEOUT (30*HZ)
/* flags for v9fs_stat2inode() & v9fs_stat2inode_dotl() */
#define V9FS_STAT2INODE_KEEP_ISIZE 1
extern struct file_system_type v9fs_fs_type;
extern const struct address_space_operations v9fs_addr_operations;
extern const struct file_operations v9fs_file_operations;
extern const struct file_operations v9fs_file_operations_dotl;
extern const struct file_operations v9fs_dir_operations;
extern const struct file_operations v9fs_dir_operations_dotl;
extern const struct dentry_operations v9fs_dentry_operations;
extern const struct dentry_operations v9fs_cached_dentry_operations;
extern struct kmem_cache *v9fs_inode_cache;
struct inode *v9fs_alloc_inode(struct super_block *sb);
void v9fs_free_inode(struct inode *inode);
void v9fs_set_netfs_context(struct inode *inode);
int v9fs_init_inode(struct v9fs_session_info *v9ses,
struct inode *inode, umode_t mode, dev_t rdev);
void v9fs_evict_inode(struct inode *inode);
#if (BITS_PER_LONG == 32)
#define QID2INO(q) ((ino_t) (((q)->path+2) ^ (((q)->path) >> 32)))
#else
#define QID2INO(q) ((ino_t) ((q)->path+2))
#endif
void v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
struct super_block *sb, unsigned int flags);
void v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode,
unsigned int flags);
int v9fs_dir_release(struct inode *inode, struct file *filp);
int v9fs_file_open(struct inode *inode, struct file *file);
int v9fs_uflags2omode(int uflags, int extended);
void v9fs_blank_wstat(struct p9_wstat *wstat);
int v9fs_vfs_setattr_dotl(struct mnt_idmap *idmap,
struct dentry *dentry, struct iattr *iattr);
int v9fs_file_fsync_dotl(struct file *filp, loff_t start, loff_t end,
int datasync);
int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode);
int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode);
static inline void v9fs_invalidate_inode_attr(struct inode *inode)
{
struct v9fs_inode *v9inode;
v9inode = V9FS_I(inode);
v9inode->cache_validity |= V9FS_INO_INVALID_ATTR;
}
int v9fs_open_to_dotl_flags(int flags);
#endif