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cifs: ensure that we always do cifsFileInfo_get under the spinlock 

The readpages bug is a regression that was introduced in 6993f74a5.
This also fixes a couple of similar bugs in the uncached read and write
codepaths.

Also, prevent this sort of thing in the future by having cifsFileInfo_get
take the spinlock itself, and adding a _locked variant for use in places
that are already holding the lock. The _put code has always done that
so this makes for a less confusing interface.

Cc: <stable@vger.kernel.org> # 3.5.x
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Jeff Layton 2012-07-25 14:59:54 -04:00 committed by Steve French
parent 29e20f9c65
commit 764a1b1ace
2 changed files with 15 additions and 8 deletions
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6
fs/cifs/cifsglob.h
View File

@ -765,13 +765,13 @@ struct cifs_io_parms {
* Take a reference on the file private data. Must be called with
* cifs_file_list_lock held.
*/
static inline
struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file)
static inline void
cifsFileInfo_get_locked(struct cifsFileInfo *cifs_file)
{
++cifs_file->count;
return cifs_file;
}
struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file);
void cifsFileInfo_put(struct cifsFileInfo *cifs_file);
/*

17
fs/cifs/file.c
View File

@ -284,6 +284,15 @@ cifs_new_fileinfo(__u16 fileHandle, struct file *file,
static void cifs_del_lock_waiters(struct cifsLockInfo *lock);
struct cifsFileInfo *
cifsFileInfo_get(struct cifsFileInfo *cifs_file)
{
spin_lock(&cifs_file_list_lock);
cifsFileInfo_get_locked(cifs_file);
spin_unlock(&cifs_file_list_lock);
return cifs_file;
}
/*
* Release a reference on the file private data. This may involve closing
* the filehandle out on the server. Must be called without holding
@ -1562,7 +1571,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
if (!open_file->invalidHandle) {
/* found a good file */
/* lock it so it will not be closed on us */
cifsFileInfo_get(open_file);
cifsFileInfo_get_locked(open_file);
spin_unlock(&cifs_file_list_lock);
return open_file;
} /* else might as well continue, and look for
@ -1614,7 +1623,7 @@ refind_writable:
if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
if (!open_file->invalidHandle) {
/* found a good writable file */
cifsFileInfo_get(open_file);
cifsFileInfo_get_locked(open_file);
spin_unlock(&cifs_file_list_lock);
return open_file;
} else {
@ -1631,7 +1640,7 @@ refind_writable:
if (inv_file) {
any_available = false;
cifsFileInfo_get(inv_file);
cifsFileInfo_get_locked(inv_file);
}
spin_unlock(&cifs_file_list_lock);
@ -3082,8 +3091,6 @@ static int cifs_readpages(struct file *file, struct address_space *mapping,
break;
}
spin_lock(&cifs_file_list_lock);
spin_unlock(&cifs_file_list_lock);
rdata->cfile = cifsFileInfo_get(open_file);
rdata->mapping = mapping;
rdata->offset = offset;