From ca83ce3d5b9ad321ee24f5870a77f0b21ac5a5de Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 12 Apr 2011 09:13:44 -0400 Subject: [PATCH] cifs: don't allow mmap'ed pages to be dirtied while under writeback (try #3) This is more or less the same patch as before, but with some merge conflicts fixed up. If a process has a dirty page mapped into its page tables, then it has the ability to change it while the client is trying to write the data out to the server. If that happens after the signature has been calculated then that signature will then be wrong, and the server will likely reset the TCP connection. This patch adds a page_mkwrite handler for CIFS that simply takes the page lock. Because the page lock is held over the life of writepage and writepages, this prevents the page from becoming writeable until the write call has completed. With this, we can also remove the "sign_zero_copy" module option and always inline the pages when writing. Signed-off-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/cifsfs.c | 4 --- fs/cifs/cifsglob.h | 1 - fs/cifs/file.c | 64 ++++++++++++++++++++++++---------------------- 3 files changed, 33 insertions(+), 36 deletions(-) diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index e3352a1ac479..5c412b33cd7c 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -81,10 +81,6 @@ module_param(echo_retries, ushort, 0644); MODULE_PARM_DESC(echo_retries, "Number of echo attempts before giving up and " "reconnecting server. Default: 5. 0 means " "never reconnect."); -bool sign_zero_copy; /* globals init to false automatically */ -module_param(sign_zero_copy, bool, 0644); -MODULE_PARM_DESC(sign_zero_copy, "Don't copy pages on write with signing " - "enabled. Default: N"); extern mempool_t *cifs_sm_req_poolp; extern mempool_t *cifs_req_poolp; extern mempool_t *cifs_mid_poolp; diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index ddb359906708..a5d1106fcbde 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -826,7 +826,6 @@ GLOBAL_EXTERN unsigned int CIFSMaxBufSize; /* max size not including hdr */ GLOBAL_EXTERN unsigned int cifs_min_rcv; /* min size of big ntwrk buf pool */ GLOBAL_EXTERN unsigned int cifs_min_small; /* min size of small buf pool */ GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/ -GLOBAL_EXTERN bool sign_zero_copy; /* don't copy written pages with signing */ /* reconnect after this many failed echo attempts */ GLOBAL_EXTERN unsigned short echo_retries; diff --git a/fs/cifs/file.c b/fs/cifs/file.c index e2d7b6bada6f..faf59529e847 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -972,6 +972,9 @@ static ssize_t cifs_write(struct cifsFileInfo *open_file, total_written += bytes_written) { rc = -EAGAIN; while (rc == -EAGAIN) { + struct kvec iov[2]; + unsigned int len; + if (open_file->invalidHandle) { /* we could deadlock if we called filemap_fdatawait from here so tell @@ -981,31 +984,14 @@ static ssize_t cifs_write(struct cifsFileInfo *open_file, if (rc != 0) break; } - if (sign_zero_copy || (pTcon->ses->server && - ((pTcon->ses->server->secMode & - (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) - == 0))) { - struct kvec iov[2]; - unsigned int len; - - len = min((size_t)cifs_sb->wsize, - write_size - total_written); - /* iov[0] is reserved for smb header */ - iov[1].iov_base = (char *)write_data + - total_written; - iov[1].iov_len = len; - rc = CIFSSMBWrite2(xid, pTcon, - open_file->netfid, len, - *poffset, &bytes_written, - iov, 1, 0); - } else - rc = CIFSSMBWrite(xid, pTcon, - open_file->netfid, - min_t(const int, cifs_sb->wsize, - write_size - total_written), - *poffset, &bytes_written, - write_data + total_written, - NULL, 0); + + len = min((size_t)cifs_sb->wsize, + write_size - total_written); + /* iov[0] is reserved for smb header */ + iov[1].iov_base = (char *)write_data + total_written; + iov[1].iov_len = len; + rc = CIFSSMBWrite2(xid, pTcon, open_file->netfid, len, + *poffset, &bytes_written, iov, 1, 0); } if (rc || (bytes_written == 0)) { if (total_written) @@ -1242,12 +1228,6 @@ static int cifs_writepages(struct address_space *mapping, } tcon = tlink_tcon(open_file->tlink); - if (!sign_zero_copy && tcon->ses->server->secMode & - (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) { - cifsFileInfo_put(open_file); - kfree(iov); - return generic_writepages(mapping, wbc); - } cifsFileInfo_put(open_file); xid = GetXid(); @@ -1982,6 +1962,24 @@ static ssize_t cifs_read(struct file *file, char *read_data, size_t read_size, return total_read; } +/* + * If the page is mmap'ed into a process' page tables, then we need to make + * sure that it doesn't change while being written back. + */ +static int +cifs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct page *page = vmf->page; + + lock_page(page); + return VM_FAULT_LOCKED; +} + +static struct vm_operations_struct cifs_file_vm_ops = { + .fault = filemap_fault, + .page_mkwrite = cifs_page_mkwrite, +}; + int cifs_file_strict_mmap(struct file *file, struct vm_area_struct *vma) { int rc, xid; @@ -1993,6 +1991,8 @@ int cifs_file_strict_mmap(struct file *file, struct vm_area_struct *vma) cifs_invalidate_mapping(inode); rc = generic_file_mmap(file, vma); + if (rc == 0) + vma->vm_ops = &cifs_file_vm_ops; FreeXid(xid); return rc; } @@ -2009,6 +2009,8 @@ int cifs_file_mmap(struct file *file, struct vm_area_struct *vma) return rc; } rc = generic_file_mmap(file, vma); + if (rc == 0) + vma->vm_ops = &cifs_file_vm_ops; FreeXid(xid); return rc; } -- 2.30.2