From 2e74c7d08b8f6e07a9ed0d76a4d6771eb0e63a4e Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <piastryyy@gmail.com>
Date: Sun, 28 Mar 2010 22:12:59 +0400
Subject: [PATCH] [CIFS] Fix page reading error with mandatory locking style
If we lock file from one process from 1 to 2 and then try to read it
from another from 0 to 1 without direct mount options, reading fails.
That's why vfs tries to read whole page and fails due the lock from
the first process.
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
---
fs/cifs/cifsfs.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 46 insertions(+), 1 deletions(-)
@@ -616,6 +616,51 @@ cifs_get_sb(struct file_system_type *fs_type,
return 0;
}
+static ssize_t cifs_sync_read(struct file *filp, char __user *buf,
+ size_t len, loff_t *ppos)
+{
+ int retval, read, posix_locking = 0;
+ struct file_lock pfLock;
+ struct cifsInodeInfo *cifsInode;
+ struct cifs_sb_info *cifs_sb;
+ struct cifsTconInfo *tcon;
+
+ cifs_sb = CIFS_SB(filp->f_path.dentry->d_sb);
+ tcon = cifs_sb->tcon;
+ if ((tcon->ses->capabilities & CAP_UNIX) &&
+ (CIFS_UNIX_FCNTL_CAP & le64_to_cpu(tcon->fsUnixInfo.Capability)) &&
+ ((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
+ posix_locking = 1;
+
+ retval = cifs_revalidate(filp->f_path.dentry);
+ if (retval < 0)
+ return (ssize_t)retval;
+
+ memset(&pfLock, 0, sizeof(pfLock));
+ pfLock.fl_type = F_RDLCK;
+ pfLock.fl_start = *ppos;
+ pfLock.fl_end = *ppos+len;
+ cifsInode = CIFS_I(filp->f_path.dentry->d_inode);
+ if (cifsInode == NULL)
+ return -ENOENT;
+
+ if (!CIFS_I(filp->f_path.dentry->d_inode)->clientCanCacheRead &&
+ !posix_locking) {
+ retval = cifs_lock(filp, F_GETLK, &pfLock);
+ if (retval < 0)
+ return (ssize_t)retval;
+ if (pfLock.fl_type == F_UNLCK)
+ read = do_sync_read(filp, buf, len, ppos);
+ else
+ return -EACCES;
+ } else
+ read = do_sync_read(filp, buf, len, ppos);
+
+ if (read == -EACCES && !posix_locking)
+ read = cifs_user_read(filp, buf, len, ppos);
+ return read;
+}
+
static ssize_t cifs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
@@ -737,7 +782,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
};
const struct file_operations cifs_file_ops = {
- .read = do_sync_read,
+ .read = cifs_sync_read,
.write = do_sync_write,
.aio_read = generic_file_aio_read,
.aio_write = cifs_file_aio_write,
--
1.6.6.1