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[CIFS] Fix locking problem around some cifs uses of i_size write 

Could cause hangs on smp systems in i_size_read on a cifs inode
whose size has been previously simultaneously updated from
different processes.

Thanks to Brian Wang for some great testing/debugging on this
hard problem.

Fixes kernel bugzilla #7903

CC: Shirish Pargoankar <shirishp@us.ibm.com>
CC: Shaggy <shaggy@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Steve French 2007-02-26 16:46:11 +00:00
parent 9654640d0a
commit 3677db10a6
4 changed files with 82 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
fs/cifs/CHANGES
View File

@ -1,3 +1,9 @@
Verison 1.48
------------
Fix mtime bouncing around from local idea of last write times to remote time.
Fix hang (in i_size_read) when simultaneous size update of same remote file
on smp system corrupts sequence number.
Version 1.47
------------
Fix oops in list_del during mount caused by unaligned string.

19
fs/cifs/file.c
View File

@ -879,19 +879,20 @@ ssize_t cifs_user_write(struct file *file, const char __user *write_data,
cifs_stats_bytes_written(pTcon, total_written);
/* since the write may have blocked check these pointers again */
if (file->f_path.dentry) {
if (file->f_path.dentry->d_inode) {
if ((file->f_path.dentry) && (file->f_path.dentry->d_inode)) {
struct inode *inode = file->f_path.dentry->d_inode;
inode->i_ctime = inode->i_mtime =
current_fs_time(inode->i_sb);
/* Do not update local mtime - server will set its actual value on write
* inode->i_ctime = inode->i_mtime =
* current_fs_time(inode->i_sb);*/
if (total_written > 0) {
spin_lock(&inode->i_lock);
if (*poffset > file->f_path.dentry->d_inode->i_size)
i_size_write(file->f_path.dentry->d_inode,
*poffset);
spin_unlock(&inode->i_lock);
}
mark_inode_dirty_sync(file->f_path.dentry->d_inode);
}
}
FreeXid(xid);
return total_written;
}
@ -1012,19 +1013,19 @@ static ssize_t cifs_write(struct file *file, const char *write_data,
cifs_stats_bytes_written(pTcon, total_written);
/* since the write may have blocked check these pointers again */
if (file->f_path.dentry) {
if (file->f_path.dentry->d_inode) {
if ((file->f_path.dentry) && (file->f_path.dentry->d_inode)) {
/*BB We could make this contingent on superblock ATIME flag too */
/* file->f_path.dentry->d_inode->i_ctime =
file->f_path.dentry->d_inode->i_mtime = CURRENT_TIME;*/
if (total_written > 0) {
spin_lock(&file->f_path.dentry->d_inode->i_lock);
if (*poffset > file->f_path.dentry->d_inode->i_size)
i_size_write(file->f_path.dentry->d_inode,
*poffset);
spin_unlock(&file->f_path.dentry->d_inode->i_lock);
}
mark_inode_dirty_sync(file->f_path.dentry->d_inode);
}
}
FreeXid(xid);
return total_written;
}
@ -1400,6 +1401,7 @@ static int cifs_commit_write(struct file *file, struct page *page,
xid = GetXid();
cFYI(1, ("commit write for page %p up to position %lld for %d",
page, position, to));
spin_lock(&inode->i_lock);
if (position > inode->i_size) {
i_size_write(inode, position);
/* if (file->private_data == NULL) {
@ -1429,6 +1431,7 @@ static int cifs_commit_write(struct file *file, struct page *page,
cFYI(1, (" SetEOF (commit write) rc = %d", rc));
} */
}
spin_unlock(&inode->i_lock);
if (!PageUptodate(page)) {
position = ((loff_t)page->index << PAGE_CACHE_SHIFT) + offset;
/* can not rely on (or let) writepage write this data */

50
fs/cifs/inode.c
View File

@ -143,10 +143,10 @@ int cifs_get_inode_info_unix(struct inode **pinode,
inode->i_gid = le64_to_cpu(findData.Gid);
inode->i_nlink = le64_to_cpu(findData.Nlinks);
spin_lock(&inode->i_lock);
if (is_size_safe_to_change(cifsInfo, end_of_file)) {
/* can not safely change the file size here if the
client is writing to it due to potential races */
i_size_write(inode, end_of_file);
/* blksize needs to be multiple of two. So safer to default to
@ -162,6 +162,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
/* for this calculation */
inode->i_blocks = (512 - 1 + num_of_bytes) >> 9;
}
spin_unlock(&inode->i_lock);
if (num_of_bytes < end_of_file)
cFYI(1, ("allocation size less than end of file"));
@ -496,6 +497,8 @@ int cifs_get_inode_info(struct inode **pinode,
/* BB add code here -
validate if device or weird share or device type? */
}
spin_lock(&inode->i_lock);
if (is_size_safe_to_change(cifsInfo, le64_to_cpu(pfindData->EndOfFile))) {
/* can not safely shrink the file size here if the
client is writing to it due to potential races */
@ -506,6 +509,7 @@ int cifs_get_inode_info(struct inode **pinode,
inode->i_blocks = (512 - 1 + le64_to_cpu(
pfindData->AllocationSize)) >> 9;
}
spin_unlock(&inode->i_lock);
inode->i_nlink = le32_to_cpu(pfindData->NumberOfLinks);
@ -834,8 +838,10 @@ int cifs_rmdir(struct inode *inode, struct dentry *direntry)
if (!rc) {
drop_nlink(inode);
spin_lock(&direntry->d_inode->i_lock);
i_size_write(direntry->d_inode,0);
clear_nlink(direntry->d_inode);
spin_unlock(&direntry->d_inode->i_lock);
}
cifsInode = CIFS_I(direntry->d_inode);
@ -1128,6 +1134,46 @@ static int cifs_truncate_page(struct address_space *mapping, loff_t from)
return rc;
}
int cifs_vmtruncate(struct inode * inode, loff_t offset)
{
struct address_space *mapping = inode->i_mapping;
unsigned long limit;
if (inode->i_size < offset)
goto do_expand;
/*
* truncation of in-use swapfiles is disallowed - it would cause
* subsequent swapout to scribble on the now-freed blocks.
*/
if (IS_SWAPFILE(inode))
goto out_busy;
spin_lock(&inode->i_lock);
i_size_write(inode, offset);
spin_unlock(&inode->i_lock);
unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1);
truncate_inode_pages(mapping, offset);
goto out_truncate;
do_expand:
limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
if (limit != RLIM_INFINITY && offset > limit)
goto out_sig;
if (offset > inode->i_sb->s_maxbytes)
goto out_big;
i_size_write(inode, offset);
out_truncate:
if (inode->i_op && inode->i_op->truncate)
inode->i_op->truncate(inode);
return 0;
out_sig:
send_sig(SIGXFSZ, current, 0);
out_big:
return -EFBIG;
out_busy:
return -ETXTBSY;
}
int cifs_setattr(struct dentry *direntry, struct iattr *attrs)
{
int xid;
@ -1244,7 +1290,7 @@ int cifs_setattr(struct dentry *direntry, struct iattr *attrs)
*/
if (rc == 0) {
rc = vmtruncate(direntry->d_inode, attrs->ia_size);
rc = cifs_vmtruncate(direntry->d_inode, attrs->ia_size);
cifs_truncate_page(direntry->d_inode->i_mapping,
direntry->d_inode->i_size);
} else

6
fs/cifs/readdir.c
View File

@ -3,7 +3,7 @@
*
* Directory search handling
*
* Copyright (C) International Business Machines Corp., 2004, 2005
* Copyright (C) International Business Machines Corp., 2004, 2007
* Author(s): Steve French (sfrench@us.ibm.com)
*
* This library is free software; you can redistribute it and/or modify
@ -226,6 +226,7 @@ static void fill_in_inode(struct inode *tmp_inode, int new_buf_type,
atomic_set(&cifsInfo->inUse, 1);
}
spin_lock(&tmp_inode->i_lock);
if (is_size_safe_to_change(cifsInfo, end_of_file)) {
/* can not safely change the file size here if the
client is writing to it due to potential races */
@ -235,6 +236,7 @@ static void fill_in_inode(struct inode *tmp_inode, int new_buf_type,
/* for this calculation, even though the reported blocksize is larger */
tmp_inode->i_blocks = (512 - 1 + allocation_size) >> 9;
}
spin_unlock(&tmp_inode->i_lock);
if (allocation_size < end_of_file)
cFYI(1, ("May be sparse file, allocation less than file size"));
@ -355,6 +357,7 @@ static void unix_fill_in_inode(struct inode *tmp_inode,
tmp_inode->i_gid = le64_to_cpu(pfindData->Gid);
tmp_inode->i_nlink = le64_to_cpu(pfindData->Nlinks);
spin_lock(&tmp_inode->i_lock);
if (is_size_safe_to_change(cifsInfo, end_of_file)) {
/* can not safely change the file size here if the
client is writing to it due to potential races */
@ -364,6 +367,7 @@ static void unix_fill_in_inode(struct inode *tmp_inode,
/* for this calculation, not the real blocksize */
tmp_inode->i_blocks = (512 - 1 + num_of_bytes) >> 9;
}
spin_unlock(&tmp_inode->i_lock);
if (S_ISREG(tmp_inode->i_mode)) {
cFYI(1, ("File inode"));