From b5782e2d462c028096f922abca46318cec890670 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 12 May 2026 13:33:40 +0100 Subject: netfs: Fix missing barriers when accessing stream->subrequests locklessly The list of subrequests attached to stream->subrequests is accessed without locks by netfs_collect_read_results() and netfs_collect_write_results(), and then they access subreq->flags without taking a barrier after getting the subreq pointer from the list. Relatedly, the functions that build the list don't use any sort of write barrier when constructing the list to make sure that the NETFS_SREQ_IN_PROGRESS flag is perceived to be set first if no lock is taken. Fix this by: (1) Add a new list_add_tail_release() function that uses a release barrier to set the pointer to the new member of the list. (2) Add a new list_first_entry_or_null_acquire() function that uses an acquire barrier to read the pointer to the first member in a list (or return NULL). (3) Use list_add_tail_release() when adding a subreq to ->subrequests. (4) Use list_first_entry_or_null_acquire() when initially accessing the front of the list (when an item is removed, the pointer to the new front iterm is obtained under the same lock). Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item") Fixes: 288ace2f57c9 ("netfs: New writeback implementation") Link: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-4-dhowells@redhat.com cc: Paulo Alcantara cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- include/linux/list.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) (limited to 'include/linux') diff --git a/include/linux/list.h b/include/linux/list.h index 00ea8e5fb88b..09d979976b3b 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -191,6 +191,29 @@ static inline void list_add_tail(struct list_head *new, struct list_head *head) __list_add(new, head->prev, head); } +/** + * list_add_tail_release - add a new entry with release barrier + * @new: new entry to be added + * @head: list head to add it before + * + * Insert a new entry before the specified head, using a release barrier to set + * the ->next pointer that points to it. This is useful for implementing + * queues, in particular one that the elements will be walked through forwards + * locklessly. + */ +static inline void list_add_tail_release(struct list_head *new, + struct list_head *head) +{ + struct list_head *prev = head->prev; + + if (__list_add_valid(new, prev, head)) { + new->next = head; + new->prev = prev; + head->prev = new; + smp_store_release(&prev->next, new); + } +} + /* * Delete a list entry by making the prev/next entries * point to each other. @@ -644,6 +667,20 @@ static inline void list_splice_tail_init(struct list_head *list, pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ }) +/** + * list_first_entry_or_null_acquire - get the first element from a list with barrier + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_head within the struct. + * + * Note that if the list is empty, it returns NULL. + */ +#define list_first_entry_or_null_acquire(ptr, type, member) ({ \ + struct list_head *head__ = (ptr); \ + struct list_head *pos__ = smp_load_acquire(&head__->next); \ + pos__ != head__ ? list_entry(pos__, type, member) : NULL; \ +}) + /** * list_last_entry_or_null - get the last element from a list * @ptr: the list head to take the element from. -- cgit v1.3-14-g43fede From 2c8f4742bb76117d735f92a3932d85239b16c494 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 12 May 2026 13:33:42 +0100 Subject: 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: 4058f742105e ("netfs: Keep track of the actual remote file size") Fixes: 100ccd18bb41 ("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 Link: https://patch.msgid.link/20260512123404.719402-6-dhowells@redhat.com cc: Paulo Alcantara cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- fs/9p/v9fs_vfs.h | 13 -- fs/9p/vfs_inode.c | 6 +- fs/9p/vfs_inode_dotl.c | 12 +- fs/afs/file.c | 24 +++- fs/afs/inode.c | 31 +++-- fs/afs/internal.h | 11 +- fs/afs/write.c | 2 +- fs/netfs/buffered_read.c | 6 +- fs/netfs/buffered_write.c | 2 +- fs/netfs/direct_write.c | 6 +- fs/netfs/misc.c | 32 +++-- fs/netfs/write_collect.c | 9 +- fs/smb/client/cifsfs.c | 38 ++++-- fs/smb/client/cifssmb.c | 3 +- fs/smb/client/file.c | 13 +- fs/smb/client/inode.c | 14 ++- fs/smb/client/readdir.c | 3 +- fs/smb/client/smb2ops.c | 42 ++++--- fs/smb/client/smb2pdu.c | 3 +- include/linux/netfs.h | 293 ++++++++++++++++++++++++++++++++++++++++++++-- 20 files changed, 450 insertions(+), 113 deletions(-) (limited to 'include/linux') diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h index d3aefbec4de6..34c115d7c250 100644 --- a/fs/9p/v9fs_vfs.h +++ b/fs/9p/v9fs_vfs.h @@ -75,17 +75,4 @@ static inline void v9fs_invalidate_inode_attr(struct inode *inode) int v9fs_open_to_dotl_flags(int flags); -static inline void v9fs_i_size_write(struct inode *inode, loff_t i_size) -{ - /* - * 32-bit need the lock, concurrent updates could break the - * sequences and make i_size_read() loop forever. - * 64-bit updates are atomic and can skip the locking. - */ - if (sizeof(i_size) > sizeof(long)) - spin_lock(&inode->i_lock); - i_size_write(inode, i_size); - if (sizeof(i_size) > sizeof(long)) - spin_unlock(&inode->i_lock); -} #endif diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c index d1508b1fe109..f468acb8ee7d 100644 --- a/fs/9p/vfs_inode.c +++ b/fs/9p/vfs_inode.c @@ -1141,11 +1141,13 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode, mode |= inode->i_mode & ~S_IALLUGO; inode->i_mode = mode; - v9inode->netfs.remote_i_size = stat->length; + spin_lock(&inode->i_lock); + netfs_write_remote_i_size(inode, stat->length); if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE)) - v9fs_i_size_write(inode, stat->length); + i_size_write(inode, stat->length); /* not real number of blocks, but 512 byte ones ... */ inode->i_blocks = (stat->length + 512 - 1) >> 9; + spin_unlock(&inode->i_lock); v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR; } diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c index 71796a89bcf4..141fb54db65d 100644 --- a/fs/9p/vfs_inode_dotl.c +++ b/fs/9p/vfs_inode_dotl.c @@ -634,10 +634,12 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode, mode |= inode->i_mode & ~S_IALLUGO; inode->i_mode = mode; - v9inode->netfs.remote_i_size = stat->st_size; + spin_lock(&inode->i_lock); + netfs_write_remote_i_size(inode, stat->st_size); if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE)) - v9fs_i_size_write(inode, stat->st_size); + i_size_write(inode, stat->st_size); inode->i_blocks = stat->st_blocks; + spin_unlock(&inode->i_lock); } else { if (stat->st_result_mask & P9_STATS_ATIME) { inode_set_atime(inode, stat->st_atime_sec, @@ -662,13 +664,15 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode, mode |= inode->i_mode & ~S_IALLUGO; inode->i_mode = mode; } + spin_lock(&inode->i_lock); if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE) && stat->st_result_mask & P9_STATS_SIZE) { - v9inode->netfs.remote_i_size = stat->st_size; - v9fs_i_size_write(inode, stat->st_size); + netfs_write_remote_i_size(inode, stat->st_size); + i_size_write(inode, stat->st_size); } if (stat->st_result_mask & P9_STATS_BLOCKS) inode->i_blocks = stat->st_blocks; + spin_unlock(&inode->i_lock); } if (stat->st_result_mask & P9_STATS_GEN) inode->i_generation = stat->st_gen; diff --git a/fs/afs/file.c b/fs/afs/file.c index 85696ac984cc..0467742bfeee 100644 --- a/fs/afs/file.c +++ b/fs/afs/file.c @@ -427,21 +427,35 @@ static void afs_free_request(struct netfs_io_request *rreq) afs_put_wb_key(rreq->netfs_priv2); } -static void afs_update_i_size(struct inode *inode, loff_t new_i_size) +/* + * Set the file size and block count, taking ->cb_lock and ->i_lock to maintain + * coherency and prevent 64-bit tearing on 32-bit arches. + * + * Also, estimate the number of 512 bytes blocks used, rounded up to nearest 1K + * for consistency with other AFS clients. + */ +void afs_set_i_size(struct afs_vnode *vnode, loff_t new_i_size) { - struct afs_vnode *vnode = AFS_FS_I(inode); + struct inode *inode = &vnode->netfs.inode; loff_t i_size; write_seqlock(&vnode->cb_lock); - i_size = i_size_read(&vnode->netfs.inode); + spin_lock(&inode->i_lock); + i_size = i_size_read(inode); if (new_i_size > i_size) { - i_size_write(&vnode->netfs.inode, new_i_size); - inode_set_bytes(&vnode->netfs.inode, new_i_size); + i_size_write(inode, new_i_size); + inode_set_bytes(inode, round_up(new_i_size, 1024)); } + spin_unlock(&inode->i_lock); write_sequnlock(&vnode->cb_lock); fscache_update_cookie(afs_vnode_cache(vnode), NULL, &new_i_size); } +static void afs_update_i_size(struct inode *inode, loff_t new_i_size) +{ + afs_set_i_size(AFS_FS_I(inode), new_i_size); +} + static void afs_netfs_invalidate_cache(struct netfs_io_request *wreq) { struct afs_vnode *vnode = AFS_FS_I(wreq->inode); diff --git a/fs/afs/inode.c b/fs/afs/inode.c index a5173434f786..19fe2e392885 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -224,7 +224,8 @@ static int afs_inode_init_from_status(struct afs_operation *op, return afs_protocol_error(NULL, afs_eproto_file_type); } - afs_set_i_size(vnode, status->size); + i_size_write(inode, status->size); + inode_set_bytes(inode, status->size); afs_set_netfs_context(vnode); vnode->invalid_before = status->data_version; @@ -253,7 +254,8 @@ static void afs_apply_status(struct afs_operation *op, { struct afs_file_status *status = &vp->scb.status; struct afs_vnode *vnode = vp->vnode; - struct inode *inode = &vnode->netfs.inode; + struct netfs_inode *ictx = &vnode->netfs; + struct inode *inode = &ictx->inode; struct timespec64 t; umode_t mode; bool unexpected_jump = false; @@ -336,6 +338,8 @@ static void afs_apply_status(struct afs_operation *op, } if (data_changed) { + unsigned long long zero_point, size = status->size; + inode_set_iversion_raw(inode, status->data_version); /* Only update the size if the data version jumped. If the @@ -343,16 +347,25 @@ static void afs_apply_status(struct afs_operation *op, * idea of what the size should be that's not the same as * what's on the server. */ - vnode->netfs.remote_i_size = status->size; - if (change_size || status->size > i_size_read(inode)) { - afs_set_i_size(vnode, status->size); + spin_lock(&inode->i_lock); + + if (change_size || size > i_size_read(inode)) { + /* We can read the sizes directly as we hold i_lock. */ + zero_point = ictx->_zero_point; + if (unexpected_jump) - vnode->netfs.zero_point = status->size; + zero_point = size; + netfs_write_sizes(inode, size, size, zero_point); + inode_set_bytes(inode, size); inode_set_ctime_to_ts(inode, t); inode_set_atime_to_ts(inode, t); + } else { + netfs_write_remote_i_size(inode, size); } + spin_unlock(&inode->i_lock); + if (op->ops == &afs_fetch_data_operation) - op->fetch.subreq->rreq->i_size = status->size; + op->fetch.subreq->rreq->i_size = size; } } @@ -709,7 +722,7 @@ int afs_getattr(struct mnt_idmap *idmap, const struct path *path, * it, but we need to give userspace the server's size. */ if (S_ISDIR(inode->i_mode)) - stat->size = vnode->netfs.remote_i_size; + stat->size = netfs_read_remote_i_size(inode); } while (read_seqretry(&vnode->cb_lock, seq)); return 0; @@ -889,7 +902,7 @@ int afs_setattr(struct mnt_idmap *idmap, struct dentry *dentry, */ if (!(attr->ia_valid & (supported & ~ATTR_SIZE & ~ATTR_MTIME)) && attr->ia_size < i_size && - attr->ia_size > vnode->netfs.remote_i_size) { + attr->ia_size > netfs_read_remote_i_size(inode)) { truncate_setsize(inode, attr->ia_size); netfs_resize_file(&vnode->netfs, size, false); fscache_resize_cookie(afs_vnode_cache(vnode), diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 599353c33337..816dc848ea71 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -1157,6 +1157,7 @@ extern int afs_open(struct inode *, struct file *); extern int afs_release(struct inode *, struct file *); void afs_fetch_data_async_rx(struct work_struct *work); void afs_fetch_data_immediate_cancel(struct afs_call *call); +void afs_set_i_size(struct afs_vnode *vnode, loff_t new_i_size); /* * flock.c @@ -1758,16 +1759,6 @@ static inline void afs_update_dentry_version(struct afs_operation *op, (void *)(unsigned long)dir_vp->scb.status.data_version; } -/* - * Set the file size and block count. Estimate the number of 512 bytes blocks - * used, rounded up to nearest 1K for consistency with other AFS clients. - */ -static inline void afs_set_i_size(struct afs_vnode *vnode, u64 size) -{ - i_size_write(&vnode->netfs.inode, size); - vnode->netfs.inode.i_blocks = ((size + 1023) >> 10) << 1; -} - /* * Check for a conflicting operation on a directory that we just unlinked from. * If someone managed to sneak a link or an unlink in on the file we just diff --git a/fs/afs/write.c b/fs/afs/write.c index fcfed9d24e0a..7f34b939706a 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -142,7 +142,7 @@ static void afs_issue_write_worker(struct work_struct *work) afs_begin_vnode_operation(op); op->store.write_iter = &subreq->io_iter; - op->store.i_size = umax(pos + len, vnode->netfs.remote_i_size); + op->store.i_size = umax(pos + len, netfs_read_remote_i_size(&vnode->netfs.inode)); op->mtime = inode_get_mtime(&vnode->netfs.inode); afs_wait_for_operation(op); diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index fee0aebf5a3d..ebd84a6cc3f0 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -209,7 +209,6 @@ static void netfs_issue_read(struct netfs_io_request *rreq, static void netfs_read_to_pagecache(struct netfs_io_request *rreq, struct readahead_control *ractl) { - struct netfs_inode *ictx = netfs_inode(rreq->inode); unsigned long long start = rreq->start; ssize_t size = rreq->len; int ret = 0; @@ -233,7 +232,8 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq, source = netfs_cache_prepare_read(rreq, subreq, rreq->i_size); subreq->source = source; if (source == NETFS_DOWNLOAD_FROM_SERVER) { - unsigned long long zp = umin(ictx->zero_point, rreq->i_size); + unsigned long long zero_point = netfs_read_zero_point(rreq->inode); + unsigned long long zp = umin(zero_point, rreq->i_size); size_t len = subreq->len; if (unlikely(rreq->origin == NETFS_READ_SINGLE)) @@ -249,7 +249,7 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq, pr_err("ZERO-LEN READ: R=%08x[%x] l=%zx/%zx s=%llx z=%llx i=%llx", rreq->debug_id, subreq->debug_index, subreq->len, size, - subreq->start, ictx->zero_point, rreq->i_size); + subreq->start, zero_point, rreq->i_size); netfs_cancel_read(subreq, ret); break; } diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c index 05ea5b0cc0e8..b6ecd059dc4f 100644 --- a/fs/netfs/buffered_write.c +++ b/fs/netfs/buffered_write.c @@ -230,7 +230,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, * server would just return a block of zeros or a short read if * we try to read it. */ - if (fpos >= ctx->zero_point) { + if (fpos >= netfs_read_zero_point(inode)) { folio_zero_segment(folio, 0, offset); copied = copy_folio_from_iter_atomic(folio, offset, part, iter); if (unlikely(copied == 0)) diff --git a/fs/netfs/direct_write.c b/fs/netfs/direct_write.c index f9ab69de3e29..25f8ceb15fad 100644 --- a/fs/netfs/direct_write.c +++ b/fs/netfs/direct_write.c @@ -376,8 +376,10 @@ ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) if (ret < 0) goto out; end = iocb->ki_pos + iov_iter_count(from); - if (end > ictx->zero_point) - ictx->zero_point = end; + spin_lock(&inode->i_lock); + if (end > ictx->_zero_point) + netfs_write_zero_point(inode, end); + spin_unlock(&inode->i_lock); fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode), FSCACHE_INVAL_DIO_WRITE); diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 21357907b7ee..bad661ff2bec 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -211,18 +211,25 @@ EXPORT_SYMBOL(netfs_clear_inode_writeback); void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) { struct netfs_folio *finfo; - struct netfs_inode *ctx = netfs_inode(folio_inode(folio)); + struct inode *inode = folio_inode(folio); + struct netfs_inode *ctx = netfs_inode(inode); size_t flen = folio_size(folio); _enter("{%lx},%zx,%zx", folio->index, offset, length); if (offset == 0 && length == flen) { - unsigned long long i_size = i_size_read(&ctx->inode); + unsigned long long i_size, remote_i_size, zero_point; unsigned long long fpos = folio_pos(folio), end; + netfs_read_sizes(inode, &i_size, &remote_i_size, &zero_point); end = umin(fpos + flen, i_size); - if (fpos < i_size && end > ctx->zero_point) - ctx->zero_point = end; + if (fpos < i_size && end > zero_point) { + spin_lock(&inode->i_lock); + end = umin(fpos + flen, inode->i_size); + if (fpos < i_size && end > ctx->_zero_point) + netfs_write_zero_point(inode, end); + spin_unlock(&inode->i_lock); + } } folio_wait_private_2(folio); /* [DEPRECATED] */ @@ -292,15 +299,22 @@ EXPORT_SYMBOL(netfs_invalidate_folio); */ bool netfs_release_folio(struct folio *folio, gfp_t gfp) { - struct netfs_inode *ctx = netfs_inode(folio_inode(folio)); - unsigned long long end; + struct inode *inode = folio_inode(folio); + struct netfs_inode *ctx = netfs_inode(inode); + unsigned long long i_size, remote_i_size, zero_point, end; if (folio_test_dirty(folio)) return false; - end = umin(folio_next_pos(folio), i_size_read(&ctx->inode)); - if (end > ctx->zero_point) - ctx->zero_point = end; + netfs_read_sizes(inode, &i_size, &remote_i_size, &zero_point); + end = umin(folio_next_pos(folio), i_size); + if (end > zero_point) { + spin_lock(&inode->i_lock); + end = umin(folio_next_pos(folio), inode->i_size); + if (end > ctx->_zero_point) + netfs_write_zero_point(inode, end); + spin_unlock(&inode->i_lock); + } if (folio_test_private(folio)) return false; diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c index 7fbf50907a7f..24fc2bb2f8a4 100644 --- a/fs/netfs/write_collect.c +++ b/fs/netfs/write_collect.c @@ -57,7 +57,8 @@ static void netfs_dump_request(const struct netfs_io_request *rreq) int netfs_folio_written_back(struct folio *folio) { enum netfs_folio_trace why = netfs_folio_trace_clear; - struct netfs_inode *ictx = netfs_inode(folio->mapping->host); + struct inode *inode = folio_inode(folio); + struct netfs_inode *ictx = netfs_inode(inode); struct netfs_folio *finfo; struct netfs_group *group = NULL; int gcount = 0; @@ -69,8 +70,10 @@ int netfs_folio_written_back(struct folio *folio) unsigned long long fend; fend = folio_pos(folio) + finfo->dirty_offset + finfo->dirty_len; - if (fend > ictx->zero_point) - ictx->zero_point = fend; + spin_lock(&ictx->inode.i_lock); + if (fend > ictx->_zero_point) + netfs_write_zero_point(inode, fend); + spin_unlock(&ictx->inode.i_lock); folio_detach_private(folio); group = finfo->netfs_group; diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c index 9f76b0347fa9..feac491c5070 100644 --- a/fs/smb/client/cifsfs.c +++ b/fs/smb/client/cifsfs.c @@ -434,7 +434,8 @@ cifs_alloc_inode(struct super_block *sb) spin_lock_init(&cifs_inode->writers_lock); cifs_inode->writers = 0; cifs_inode->netfs.inode.i_blkbits = 14; /* 2**14 = CIFS_MAX_MSGSIZE */ - cifs_inode->netfs.remote_i_size = 0; + cifs_inode->netfs._remote_i_size = 0; + cifs_inode->netfs._zero_point = 0; cifs_inode->uniqueid = 0; cifs_inode->createtime = 0; cifs_inode->epoch = 0; @@ -1303,7 +1304,8 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, struct cifsFileInfo *smb_file_src = src_file->private_data; struct cifsFileInfo *smb_file_target = dst_file->private_data; struct cifs_tcon *target_tcon, *src_tcon; - unsigned long long destend, fstart, fend, old_size, new_size; + unsigned long long i_size, old_size, new_size, zero_point; + unsigned long long destend, fstart, fend; unsigned int xid; int rc; @@ -1347,7 +1349,7 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, * Advance the EOF marker after the flush above to the end of the range * if it's short of that. */ - if (src_cifsi->netfs.remote_i_size < off + len) { + if (netfs_read_remote_i_size(src_inode) < off + len) { rc = cifs_precopy_set_eof(src_inode, src_cifsi, src_tcon, xid, off + len); if (rc < 0) goto unlock; @@ -1368,16 +1370,18 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, rc = cifs_flush_folio(target_inode, destend, &fstart, &fend, false); if (rc) goto unlock; - if (fend > target_cifsi->netfs.zero_point) - target_cifsi->netfs.zero_point = fend + 1; - old_size = target_cifsi->netfs.remote_i_size; + + spin_lock(&target_inode->i_lock); + if (fend > zero_point) + netfs_write_zero_point(target_inode, fend + 1); + i_size = target_inode->i_size; + spin_unlock(&target_inode->i_lock); /* Discard all the folios that overlap the destination region. */ cifs_dbg(FYI, "about to discard pages %llx-%llx\n", fstart, fend); truncate_inode_pages_range(&target_inode->i_data, fstart, fend); - fscache_invalidate(cifs_inode_cookie(target_inode), NULL, - i_size_read(target_inode), 0); + fscache_invalidate(cifs_inode_cookie(target_inode), NULL, i_size, 0); rc = -EOPNOTSUPP; if (target_tcon->ses->server->ops->duplicate_extents) { @@ -1402,8 +1406,12 @@ static loff_t cifs_remap_file_range(struct file *src_file, loff_t off, rc = -EINVAL; } } - if (rc == 0 && new_size > target_cifsi->netfs.zero_point) - target_cifsi->netfs.zero_point = new_size; + if (rc == 0) { + spin_lock(&target_inode->i_lock); + if (new_size > target_cifsi->netfs._zero_point) + netfs_write_zero_point(target_inode, new_size); + spin_unlock(&target_inode->i_lock); + } } /* force revalidate of size and timestamps of target file now @@ -1474,7 +1482,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, * Advance the EOF marker after the flush above to the end of the range * if it's short of that. */ - if (src_cifsi->netfs.remote_i_size < off + len) { + if (netfs_read_remote_i_size(src_inode) < off + len) { rc = cifs_precopy_set_eof(src_inode, src_cifsi, src_tcon, xid, off + len); if (rc < 0) goto unlock; @@ -1502,8 +1510,12 @@ ssize_t cifs_file_copychunk_range(unsigned int xid, fscache_resize_cookie(cifs_inode_cookie(target_inode), i_size_read(target_inode)); } - if (rc > 0 && destoff + rc > target_cifsi->netfs.zero_point) - target_cifsi->netfs.zero_point = destoff + rc; + if (rc > 0) { + spin_lock(&target_inode->i_lock); + if (destoff + rc > target_cifsi->netfs._zero_point) + netfs_write_zero_point(target_inode, destoff + rc); + spin_unlock(&target_inode->i_lock); + } } file_accessed(src_file); diff --git a/fs/smb/client/cifssmb.c b/fs/smb/client/cifssmb.c index 3990a9012264..9e27bfa7376b 100644 --- a/fs/smb/client/cifssmb.c +++ b/fs/smb/client/cifssmb.c @@ -1465,6 +1465,7 @@ cifs_readv_callback(struct TCP_Server_Info *server, struct mid_q_entry *mid) struct cifs_io_subrequest *rdata = mid->callback_data; struct netfs_inode *ictx = netfs_inode(rdata->rreq->inode); struct cifs_tcon *tcon = tlink_tcon(rdata->req->cfile->tlink); + struct inode *inode = &ictx->inode; struct smb_rqst rqst = { .rq_iov = rdata->iov, .rq_nvec = 1, .rq_iter = rdata->subreq.io_iter }; @@ -1538,7 +1539,7 @@ do_retry: } else { size_t trans = rdata->subreq.transferred + rdata->got_bytes; if (trans < rdata->subreq.len && - rdata->subreq.start + trans >= ictx->remote_i_size) { + rdata->subreq.start + trans >= netfs_read_remote_i_size(inode)) { rdata->result = 0; __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags); } else if (rdata->got_bytes > 0) { diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c index 664a2c223089..b60344125f27 100644 --- a/fs/smb/client/file.c +++ b/fs/smb/client/file.c @@ -2517,18 +2517,23 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *flock) void cifs_write_subrequest_terminated(struct cifs_io_subrequest *wdata, ssize_t result) { struct netfs_io_request *wreq = wdata->rreq; - struct netfs_inode *ictx = netfs_inode(wreq->inode); + struct inode *inode = wreq->inode; + struct netfs_inode *ictx = netfs_inode(inode); loff_t wrend; if (result > 0) { + spin_lock(&inode->i_lock); + wrend = wdata->subreq.start + wdata->subreq.transferred + result; - if (wrend > ictx->zero_point && + if (wrend > ictx->_zero_point && (wdata->rreq->origin == NETFS_UNBUFFERED_WRITE || wdata->rreq->origin == NETFS_DIO_WRITE)) - ictx->zero_point = wrend; - if (wrend > ictx->remote_i_size) + netfs_write_zero_point(inode, wrend); + if (wrend > ictx->_remote_i_size) netfs_resize_file(ictx, wrend, true); + + spin_unlock(&inode->i_lock); } netfs_write_subrequest_terminated(&wdata->subreq, result); diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c index 16a5310155d5..9472c0a6c187 100644 --- a/fs/smb/client/inode.c +++ b/fs/smb/client/inode.c @@ -119,7 +119,7 @@ cifs_revalidate_cache(struct inode *inode, struct cifs_fattr *fattr) fattr->cf_mtime = timestamp_truncate(fattr->cf_mtime, inode); mtime = inode_get_mtime(inode); if (timespec64_equal(&mtime, &fattr->cf_mtime) && - cifs_i->netfs.remote_i_size == fattr->cf_eof) { + netfs_read_remote_i_size(inode) == fattr->cf_eof) { cifs_dbg(FYI, "%s: inode %llu is unchanged\n", __func__, cifs_i->uniqueid); return; @@ -173,12 +173,12 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr, CIFS_I(inode)->time = 0; /* force reval */ return -ESTALE; } - if (inode_state_read_once(inode) & I_NEW) - CIFS_I(inode)->netfs.zero_point = fattr->cf_eof; - cifs_revalidate_cache(inode, fattr); spin_lock(&inode->i_lock); + if (inode_state_read_once(inode) & I_NEW) + netfs_write_zero_point(inode, fattr->cf_eof); + fattr->cf_mtime = timestamp_truncate(fattr->cf_mtime, inode); fattr->cf_atime = timestamp_truncate(fattr->cf_atime, inode); fattr->cf_ctime = timestamp_truncate(fattr->cf_ctime, inode); @@ -212,7 +212,7 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr, else clear_bit(CIFS_INO_DELETE_PENDING, &cifs_i->flags); - cifs_i->netfs.remote_i_size = fattr->cf_eof; + netfs_write_remote_i_size(inode, fattr->cf_eof); /* * Can't safely change the file size here if the client is writing to * it due to potential races. @@ -2772,7 +2772,9 @@ cifs_revalidate_mapping(struct inode *inode) if (cifs_sb_flags(cifs_sb) & CIFS_MOUNT_RW_CACHE) goto skip_invalidate; - cifs_inode->netfs.zero_point = cifs_inode->netfs.remote_i_size; + spin_lock(&inode->i_lock); + netfs_write_zero_point(inode, netfs_inode(inode)->_remote_i_size); + spin_unlock(&inode->i_lock); rc = filemap_invalidate_inode(inode, true, 0, LLONG_MAX); if (rc) { cifs_dbg(VFS, "%s: invalidate inode %p failed with rc %d\n", diff --git a/fs/smb/client/readdir.c b/fs/smb/client/readdir.c index be22bbc4a65a..e860fa08b5e3 100644 --- a/fs/smb/client/readdir.c +++ b/fs/smb/client/readdir.c @@ -143,7 +143,8 @@ retry: fattr->cf_rdev = inode->i_rdev; fattr->cf_uid = inode->i_uid; fattr->cf_gid = inode->i_gid; - fattr->cf_eof = CIFS_I(inode)->netfs.remote_i_size; + fattr->cf_eof = + netfs_read_remote_i_size(inode); fattr->cf_symlink_target = NULL; } else { CIFS_I(inode)->time = 0; diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c index e6cb9b144530..0ea3ce1b94ea 100644 --- a/fs/smb/client/smb2ops.c +++ b/fs/smb/client/smb2ops.c @@ -3402,8 +3402,7 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon, struct inode *inode = file_inode(file); struct cifsInodeInfo *cifsi = CIFS_I(inode); struct cifsFileInfo *cfile = file->private_data; - struct netfs_inode *ictx = netfs_inode(inode); - unsigned long long i_size, new_size, remote_size; + unsigned long long i_size, new_size, remote_i_size, zero_point; long rc; unsigned int xid; @@ -3414,9 +3413,8 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon, filemap_invalidate_lock(inode->i_mapping); - i_size = i_size_read(inode); - remote_size = ictx->remote_i_size; - if (offset + len >= remote_size && offset < i_size) { + netfs_read_sizes(inode, &i_size, &remote_i_size, &zero_point); + if (offset + len >= remote_i_size && offset < i_size) { unsigned long long top = umin(offset + len, i_size); rc = filemap_write_and_wait_range(inode->i_mapping, offset, top - 1); @@ -3449,9 +3447,11 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon, cfile->fid.volatile_fid, cfile->pid, new_size); if (rc >= 0) { truncate_setsize(inode, new_size); + spin_lock(&inode->i_lock); netfs_resize_file(&cifsi->netfs, new_size, true); - if (offset < cifsi->netfs.zero_point) - cifsi->netfs.zero_point = offset; + if (offset < cifsi->netfs._zero_point) + netfs_write_zero_point(inode, offset); + spin_unlock(&inode->i_lock); fscache_resize_cookie(cifs_inode_cookie(inode), new_size); } } @@ -3474,7 +3474,7 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, struct inode *inode = file_inode(file); struct cifsFileInfo *cfile = file->private_data; struct file_zero_data_information fsctl_buf; - unsigned long long end = offset + len, i_size, remote_i_size; + unsigned long long end = offset + len, i_size, remote_i_size, zero_point; long rc; unsigned int xid; __u8 set_sparse = 1; @@ -3516,14 +3516,17 @@ static long smb3_punch_hole(struct file *file, struct cifs_tcon *tcon, * that we locally hole-punch the tail of the dirty data, the proposed * EOF update will end up in the wrong place. */ - i_size = i_size_read(inode); - remote_i_size = netfs_inode(inode)->remote_i_size; + netfs_read_sizes(inode, &i_size, &remote_i_size, &zero_point); + if (end > remote_i_size && i_size > remote_i_size) { unsigned long long extend_to = umin(end, i_size); rc = SMB2_set_eof(xid, tcon, cfile->fid.persistent_fid, cfile->fid.volatile_fid, cfile->pid, extend_to); - if (rc >= 0) - netfs_inode(inode)->remote_i_size = extend_to; + if (rc >= 0) { + spin_lock(&inode->i_lock); + netfs_write_remote_i_size(inode, extend_to); + spin_unlock(&inode->i_lock); + } } unlock: @@ -3787,7 +3790,6 @@ static long smb3_collapse_range(struct file *file, struct cifs_tcon *tcon, struct inode *inode = file_inode(file); struct cifsInodeInfo *cifsi = CIFS_I(inode); struct cifsFileInfo *cfile = file->private_data; - struct netfs_inode *ictx = &cifsi->netfs; loff_t old_eof, new_eof; xid = get_xid(); @@ -3805,7 +3807,9 @@ static long smb3_collapse_range(struct file *file, struct cifs_tcon *tcon, goto out_2; truncate_pagecache_range(inode, off, old_eof); - ictx->zero_point = old_eof; + spin_lock(&inode->i_lock); + netfs_write_zero_point(inode, old_eof); + spin_unlock(&inode->i_lock); netfs_wait_for_outstanding_io(inode); rc = smb2_copychunk_range(xid, cfile, cfile, off + len, @@ -3822,8 +3826,10 @@ static long smb3_collapse_range(struct file *file, struct cifs_tcon *tcon, rc = 0; truncate_setsize(inode, new_eof); + spin_lock(&inode->i_lock); netfs_resize_file(&cifsi->netfs, new_eof, true); - ictx->zero_point = new_eof; + netfs_write_zero_point(inode, new_eof); + spin_unlock(&inode->i_lock); fscache_resize_cookie(cifs_inode_cookie(inode), new_eof); out_2: filemap_invalidate_unlock(inode->i_mapping); @@ -3866,13 +3872,17 @@ static long smb3_insert_range(struct file *file, struct cifs_tcon *tcon, goto out_2; truncate_setsize(inode, new_eof); + spin_lock(&inode->i_lock); netfs_resize_file(&cifsi->netfs, i_size_read(inode), true); + spin_unlock(&inode->i_lock); fscache_resize_cookie(cifs_inode_cookie(inode), i_size_read(inode)); rc = smb2_copychunk_range(xid, cfile, cfile, off, count, off + len); if (rc < 0) goto out_2; - cifsi->netfs.zero_point = new_eof; + spin_lock(&inode->i_lock); + netfs_write_zero_point(inode, new_eof); + spin_unlock(&inode->i_lock); rc = smb3_zero_data(file, tcon, off, len, xid); if (rc < 0) diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 995fcdd30681..3bd300347f16 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -4608,6 +4608,7 @@ smb2_readv_callback(struct TCP_Server_Info *server, struct mid_q_entry *mid) struct netfs_inode *ictx = netfs_inode(rdata->rreq->inode); struct cifs_tcon *tcon = tlink_tcon(rdata->req->cfile->tlink); struct smb2_hdr *shdr = (struct smb2_hdr *)rdata->iov[0].iov_base; + struct inode *inode = &ictx->inode; struct cifs_credits credits = { .value = 0, .instance = 0, @@ -4721,7 +4722,7 @@ do_retry: } else { size_t trans = rdata->subreq.transferred + rdata->got_bytes; if (trans < rdata->subreq.len && - rdata->subreq.start + trans >= ictx->remote_i_size) { + rdata->subreq.start + trans >= netfs_read_remote_i_size(inode)) { __set_bit(NETFS_SREQ_HIT_EOF, &rdata->subreq.flags); rdata->result = 0; } diff --git a/include/linux/netfs.h b/include/linux/netfs.h index ba17ac5bf356..4fd1d796ad73 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -62,8 +62,8 @@ struct netfs_inode { struct fscache_cookie *cache; #endif struct mutex wb_lock; /* Writeback serialisation */ - loff_t remote_i_size; /* Size of the remote file */ - loff_t zero_point; /* Size after which we assume there's no data + loff_t _remote_i_size; /* Size of the remote file */ + loff_t _zero_point; /* Size after which we assume there's no data * on the server */ atomic_t io_count; /* Number of outstanding reqs */ unsigned long flags; @@ -474,6 +474,254 @@ static inline struct netfs_inode *netfs_inode(struct inode *inode) return container_of(inode, struct netfs_inode, inode); } +/** + * netfs_read_remote_i_size - Read remote_i_size safely + * @inode: The inode to access + * + * Read remote_i_size safely without the potential for tearing on 32-bit + * arches. + * + * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the + * i_size_read/write must be atomic with respect to the local cpu (unlike with + * preempt disabled), but they don't need to be atomic with respect to other + * cpus like in true SMP (so they need either to either locally disable irq + * around the read or for example on x86 they can be still implemented as a + * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit + * archs it makes no difference if preempt is enabled or not. + */ +static inline unsigned long long netfs_read_remote_i_size(const struct inode *inode) +{ + const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); + unsigned long long remote_i_size; + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + unsigned int seq; + + do { + seq = read_seqcount_begin(&inode->i_size_seqcount); + remote_i_size = ictx->_remote_i_size; + } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + remote_i_size = ictx->_remote_i_size; + preempt_enable(); +#else + /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ + remote_i_size = smp_load_acquire(&ictx->_remote_i_size); +#endif + return remote_i_size; +} + +/* + * netfs_write_remote_i_size - Set remote_i_size safely + * @inode: The inode to access + * @remote_i_size: The new value for the size of the file on the server + * + * Set remote_i_size safely without the potential for tearing on 32-bit arches. + * + * Context: The caller must hold inode->i_lock. + * + * NOTE: unlike netfs_read_remote_i_size(), netfs_write_remote_i_size() does + * need locking around it (normally i_rwsem), otherwise on 32bit/SMP an update + * of i_size_seqcount can be lost, resulting in subsequent i_size_read() calls + * spinning forever. + */ +static inline void netfs_write_remote_i_size(struct inode *inode, + unsigned long long remote_i_size) +{ + struct netfs_inode *ictx = netfs_inode(inode); + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + write_seqcount_begin(&inode->i_size_seqcount); + ictx->_remote_i_size = remote_i_size; + write_seqcount_end(&inode->i_size_seqcount); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + ictx->_remote_i_size = remote_i_size; + preempt_enable(); +#else + /* + * Pairs with smp_load_acquire() in netfs_read_remote_i_size() to + * ensure changes related to inode size (such as page contents) are + * visible before we see the changed inode size. + */ + smp_store_release(&ictx->_remote_i_size, remote_i_size); +#endif +} + +/** + * netfs_read_zero_point - Read zero_point safely + * @inode: The inode to access + * + * Read zero_point safely without the potential for tearing on 32-bit + * arches. + * + * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the + * i_size_read/write must be atomic with respect to the local cpu (unlike with + * preempt disabled), but they don't need to be atomic with respect to other + * cpus like in true SMP (so they need either to either locally disable irq + * around the read or for example on x86 they can be still implemented as a + * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit + * archs it makes no difference if preempt is enabled or not. + */ +static inline unsigned long long netfs_read_zero_point(const struct inode *inode) +{ + struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); + unsigned long long zero_point; + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + unsigned int seq; + + do { + seq = read_seqcount_begin(&inode->i_size_seqcount); + zero_point = ictx->_zero_point; + } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + zero_point = ictx->_zero_point; + preempt_enable(); +#else + /* Pairs with smp_store_release() in netfs_write_zero_point() */ + zero_point = smp_load_acquire(&ictx->_zero_point); +#endif + return zero_point; +} + +/* + * netfs_write_zero_point - Set zero_point safely + * @inode: The inode to access + * @zero_point: The new value for the point beyond which the server has no data + * + * Set zero_point safely without the potential for tearing on 32-bit arches. + * + * Context: The caller must hold inode->i_lock. + * + * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need + * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of + * i_size_seqcount can be lost, resulting in subsequent read calls spinning + * forever. + */ +static inline void netfs_write_zero_point(struct inode *inode, + unsigned long long zero_point) +{ + struct netfs_inode *ictx = netfs_inode(inode); + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + write_seqcount_begin(&inode->i_size_seqcount); + ictx->_zero_point = zero_point; + write_seqcount_end(&inode->i_size_seqcount); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + ictx->_zero_point = zero_point; + preempt_enable(); +#else + /* + * Pairs with smp_load_acquire() in netfs_read_zero_point() to + * ensure changes related to inode size (such as page contents) are + * visible before we see the changed inode size. + */ + smp_store_release(&ictx->_zero_point, zero_point); +#endif +} + +/** + * netfs_read_sizes - Read remote_i_size and zero_point safely + * @inode: The inode to access + * @i_size: Where to return the local file size. + * @remote_i_size: Where to return the size of the file on the server + * @zero_point: Where to return the the point beyond which the server has no data + * + * Read remote_i_size and zero_point safely without the potential for tearing + * on 32-bit arches. + * + * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the + * i_size_read/write must be atomic with respect to the local cpu (unlike with + * preempt disabled), but they don't need to be atomic with respect to other + * cpus like in true SMP (so they need either to either locally disable irq + * around the read or for example on x86 they can be still implemented as a + * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit + * archs it makes no difference if preempt is enabled or not. + */ +static inline void netfs_read_sizes(const struct inode *inode, + unsigned long long *i_size, + unsigned long long *remote_i_size, + unsigned long long *zero_point) +{ + const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + unsigned int seq; + + do { + seq = read_seqcount_begin(&inode->i_size_seqcount); + *i_size = inode->i_size; + *remote_i_size = ictx->_remote_i_size; + *zero_point = ictx->_zero_point; + } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + *i_size = inode->i_size; + *remote_i_size = ictx->_remote_i_size; + *zero_point = ictx->_zero_point; + preempt_enable(); +#else + /* Pairs with smp_store_release() in i_size_write() */ + *i_size = smp_load_acquire(&inode->i_size); + /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ + *remote_i_size = smp_load_acquire(&ictx->_remote_i_size); + /* Pairs with smp_store_release() in netfs_write_zero_point() */ + *zero_point = smp_load_acquire(&ictx->_zero_point); +#endif +} + +/* + * netfs_write_sizes - Set i_size, remote_i_size and zero_point safely + * @inode: The inode to access + * @i_size: The new value for the local size of the file + * @remote_i_size: The new value for the size of the file on the server + * @zero_point: The new value for the point beyond which the server has no data + * + * Set both remote_i_size and zero_point safely without the potential for + * tearing on 32-bit arches. + * + * Context: The caller must hold inode->i_lock. + * + * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need + * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of + * i_size_seqcount can be lost, resulting in subsequent read calls spinning + * forever. + */ +static inline void netfs_write_sizes(struct inode *inode, + unsigned long long i_size, + unsigned long long remote_i_size, + unsigned long long zero_point) +{ + struct netfs_inode *ictx = netfs_inode(inode); + +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + write_seqcount_begin(&inode->i_size_seqcount); + inode->i_size = i_size; + ictx->_remote_i_size = remote_i_size; + ictx->_zero_point = zero_point; + write_seqcount_end(&inode->i_size_seqcount); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); + inode->i_size = i_size; + ictx->_remote_i_size = remote_i_size; + ictx->_zero_point = zero_point; + preempt_enable(); +#else + /* + * Pairs with smp_load_acquire() in i_size_read(), + * netfs_read_remote_i_size() and netfs_read_zero_point() to ensure + * changes related to inode size (such as page contents) are visible + * before we see the changed inode size. + */ + smp_store_release(&inode->i_size, i_size); + smp_store_release(&ictx->_remote_i_size, remote_i_size); + smp_store_release(&ictx->_zero_point, zero_point); +#endif +} + /** * netfs_inode_init - Initialise a netfslib inode context * @ctx: The netfs inode to initialise @@ -488,8 +736,8 @@ static inline void netfs_inode_init(struct netfs_inode *ctx, bool use_zero_point) { ctx->ops = ops; - ctx->remote_i_size = i_size_read(&ctx->inode); - ctx->zero_point = LLONG_MAX; + ctx->_remote_i_size = i_size_read(&ctx->inode); + ctx->_zero_point = LLONG_MAX; ctx->flags = 0; atomic_set(&ctx->io_count, 0); #if IS_ENABLED(CONFIG_FSCACHE) @@ -498,7 +746,7 @@ static inline void netfs_inode_init(struct netfs_inode *ctx, mutex_init(&ctx->wb_lock); /* ->releasepage() drives zero_point */ if (use_zero_point) { - ctx->zero_point = ctx->remote_i_size; + ctx->_zero_point = ctx->_remote_i_size; mapping_set_release_always(ctx->inode.i_mapping); } } @@ -511,13 +759,40 @@ static inline void netfs_inode_init(struct netfs_inode *ctx, * * Inform the netfs lib that a file got resized so that it can adjust its state. */ -static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size, +static inline void netfs_resize_file(struct netfs_inode *ictx, + unsigned long long new_i_size, bool changed_on_server) { +#if BITS_PER_LONG==32 && defined(CONFIG_SMP) + struct inode *inode = &ictx->inode; + + preempt_disable(); + write_seqcount_begin(&inode->i_size_seqcount); + if (changed_on_server) + ictx->_remote_i_size = new_i_size; + if (new_i_size < ictx->_zero_point) + ictx->_zero_point = new_i_size; + write_seqcount_end(&inode->i_size_seqcount); + preempt_enable(); +#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) + preempt_disable(); if (changed_on_server) - ctx->remote_i_size = new_i_size; - if (new_i_size < ctx->zero_point) - ctx->zero_point = new_i_size; + ictx->_remote_i_size = new_i_size; + if (new_i_size < ictx->_zero_point) + ictx->_zero_point = new_i_size; + preempt_enable(); +#else + /* + * Pairs with smp_load_acquire() in netfs_read_remote_i_size and + * netfs_read_zero_point() to ensure changes related to inode size + * (such as page contents) are visible before we see the changed inode + * size. + */ + if (changed_on_server) + smp_store_release(&ictx->_remote_i_size, new_i_size); + if (new_i_size < ictx->_zero_point) + smp_store_release(&ictx->_zero_point, new_i_size); +#endif } /** -- cgit v1.3-14-g43fede From dbe556972100fabb8e5a1b3d2163831ff07b1e8e Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 12 May 2026 13:33:56 +0100 Subject: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies. Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com Signed-off-by: David Howells Link: https://patch.msgid.link/20260512123404.719402-20-dhowells@redhat.com cc: Paulo Alcantara cc: Viacheslav Dubeyko cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- fs/netfs/buffered_read.c | 4 ++-- fs/netfs/read_collect.c | 2 +- fs/netfs/read_retry.c | 2 +- include/linux/netfs.h | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index 004d426c02b4..83d0b8153e96 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -670,7 +670,7 @@ retry: ret = PTR_ERR(rreq); goto error; } - rreq->no_unlock_folio = folio->index; + rreq->no_unlock_folio = folio; __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags); ret = netfs_begin_cache_read(rreq, ctx); @@ -736,7 +736,7 @@ int netfs_prefetch_for_write(struct file *file, struct folio *folio, goto error; } - rreq->no_unlock_folio = folio->index; + rreq->no_unlock_folio = folio; __set_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags); ret = netfs_begin_cache_read(rreq, ctx); if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c index 3c9b847885c2..23660a590124 100644 --- a/fs/netfs/read_collect.c +++ b/fs/netfs/read_collect.c @@ -83,7 +83,7 @@ static void netfs_unlock_read_folio(struct netfs_io_request *rreq, } just_unlock: - if (folio->index == rreq->no_unlock_folio && + if (folio == rreq->no_unlock_folio && test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags)) { _debug("no unlock"); } else { diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c index e10eb5a07332..f59a70f3a086 100644 --- a/fs/netfs/read_retry.c +++ b/fs/netfs/read_retry.c @@ -292,7 +292,7 @@ void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq) struct folio *folio = folioq_folio(p, slot); if (folio && !folioq_is_marked2(p, slot)) { - if (folio->index == rreq->no_unlock_folio && + if (folio == rreq->no_unlock_folio && test_bit(NETFS_RREQ_NO_UNLOCK_FOLIO, &rreq->flags)) { _debug("no unlock"); diff --git a/include/linux/netfs.h b/include/linux/netfs.h index 4fd1d796ad73..243c0f737938 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -252,7 +252,7 @@ struct netfs_io_request { unsigned long long collected_to; /* Point we've collected to */ unsigned long long cleaned_to; /* Position we've cleaned folios to */ unsigned long long abandon_to; /* Position to abandon folios to */ - pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ + const struct folio *no_unlock_folio; /* Don't unlock this folio after read */ unsigned int direct_bv_count; /* Number of elements in direct_bv[] */ unsigned int debug_id; unsigned int rsize; /* Maximum read size (0 for none) */ -- cgit v1.3-14-g43fede