From ca8aa29c60238720af2ca2a5caab25fa0c70067e Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Fri, 21 Dec 2012 15:05:47 +0400 Subject: Revert "CIFS: Fix write after setting a read lock for read oplock files" that solution has data races and can end up two identical writes to the server: when clientCanCacheAll value can be changed during the execution of __generic_file_aio_write. Signed-off-by: Pavel Shilovsky Reviewed-by: Jeff Layton Signed-off-by: Steve French --- fs/cifs/file.c | 94 +++++++++++++++++++--------------------------------------- 1 file changed, 31 insertions(+), 63 deletions(-) (limited to 'fs/cifs/file.c') diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 0a6677ba212b..1b322d041f1e 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -2103,15 +2103,7 @@ static int cifs_write_end(struct file *file, struct address_space *mapping, } else { rc = copied; pos += copied; - /* - * When we use strict cache mode and cifs_strict_writev was run - * with level II oplock (indicated by leave_pages_clean field of - * CIFS_I(inode)), we can leave pages clean - cifs_strict_writev - * sent the data to the server itself. - */ - if (!CIFS_I(inode)->leave_pages_clean || - !(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_STRICT_IO)) - set_page_dirty(page); + set_page_dirty(page); } if (rc > 0) { @@ -2462,8 +2454,8 @@ ssize_t cifs_user_writev(struct kiocb *iocb, const struct iovec *iov, } static ssize_t -cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov, - unsigned long nr_segs, loff_t pos, bool cache_ex) +cifs_writev(struct kiocb *iocb, const struct iovec *iov, + unsigned long nr_segs, loff_t pos) { struct file *file = iocb->ki_filp; struct cifsFileInfo *cfile = (struct cifsFileInfo *)file->private_data; @@ -2485,12 +2477,8 @@ cifs_pagecache_writev(struct kiocb *iocb, const struct iovec *iov, server->vals->exclusive_lock_type, NULL, CIFS_WRITE_OP)) { mutex_lock(&inode->i_mutex); - if (!cache_ex) - cinode->leave_pages_clean = true; rc = __generic_file_aio_write(iocb, iov, nr_segs, - &iocb->ki_pos); - if (!cache_ex) - cinode->leave_pages_clean = false; + &iocb->ki_pos); mutex_unlock(&inode->i_mutex); } @@ -2517,62 +2505,42 @@ cifs_strict_writev(struct kiocb *iocb, const struct iovec *iov, struct cifsFileInfo *cfile = (struct cifsFileInfo *) iocb->ki_filp->private_data; struct cifs_tcon *tcon = tlink_tcon(cfile->tlink); - ssize_t written, written2; + +#ifdef CONFIG_CIFS_SMB2 /* - * We need to store clientCanCacheAll here to prevent race - * conditions - this value can be changed during an execution - * of generic_file_aio_write. For CIFS it can be changed from - * true to false only, but for SMB2 it can be changed both from - * true to false and vice versa. So, we can end up with a data - * stored in the cache, not marked dirty and not sent to the - * server if this value changes its state from false to true - * after cifs_write_end. + * If we have an oplock for read and want to write a data to the file + * we need to store it in the page cache and then push it to the server + * to be sure the next read will get a valid data. */ - bool cache_ex = cinode->clientCanCacheAll; - bool cache_read = cinode->clientCanCacheRead; - int rc; - loff_t saved_pos; + if (!cinode->clientCanCacheAll && cinode->clientCanCacheRead) { + ssize_t written; + int rc; + + written = generic_file_aio_write(iocb, iov, nr_segs, pos); + rc = filemap_fdatawrite(inode->i_mapping); + if (rc) + return (ssize_t)rc; - if (cache_ex) { - if (cap_unix(tcon->ses) && - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) && - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu( - tcon->fsUnixInfo.Capability))) - return generic_file_aio_write(iocb, iov, nr_segs, pos); - return cifs_pagecache_writev(iocb, iov, nr_segs, pos, cache_ex); + return written; } +#endif /* - * For files without exclusive oplock in strict cache mode we need to - * write the data to the server exactly from the pos to pos+len-1 rather - * than flush all affected pages because it may cause a error with - * mandatory locks on these pages but not on the region from pos to - * ppos+len-1. + * For non-oplocked files in strict cache mode we need to write the data + * to the server exactly from the pos to pos+len-1 rather than flush all + * affected pages because it may cause a error with mandatory locks on + * these pages but not on the region from pos to ppos+len-1. */ - written = cifs_user_writev(iocb, iov, nr_segs, pos); - if (!cache_read || written <= 0) - return written; - saved_pos = iocb->ki_pos; - iocb->ki_pos = pos; - /* we have a read oplock - need to store a data in the page cache */ + if (!cinode->clientCanCacheAll) + return cifs_user_writev(iocb, iov, nr_segs, pos); + if (cap_unix(tcon->ses) && - ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0) && - (CIFS_UNIX_FCNTL_CAP & le64_to_cpu( - tcon->fsUnixInfo.Capability))) - written2 = generic_file_aio_write(iocb, iov, nr_segs, pos); - else - written2 = cifs_pagecache_writev(iocb, iov, nr_segs, pos, - cache_ex); - /* errors occured during writing - invalidate the page cache */ - if (written2 < 0) { - rc = cifs_invalidate_mapping(inode); - if (rc) - written = (ssize_t)rc; - else - iocb->ki_pos = saved_pos; - } - return written; + (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) && + ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0)) + return generic_file_aio_write(iocb, iov, nr_segs, pos); + + return cifs_writev(iocb, iov, nr_segs, pos); } static struct cifs_readdata * -- cgit v1.2.3