[PATCH] fix reiserfs lock inversion of bkl vs inode semaphore
[linux-2.6.git] / fs / reiserfs / ioctl.c
1 /*
2  * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
3  */
4
5 #include <linux/capability.h>
6 #include <linux/fs.h>
7 #include <linux/reiserfs_fs.h>
8 #include <linux/time.h>
9 #include <asm/uaccess.h>
10 #include <linux/pagemap.h>
11 #include <linux/smp_lock.h>
12
13 static int reiserfs_unpack(struct inode *inode, struct file *filp);
14
15 /*
16 ** reiserfs_ioctl - handler for ioctl for inode
17 ** supported commands:
18 **  1) REISERFS_IOC_UNPACK - try to unpack tail from direct item into indirect
19 **                           and prevent packing file (argument arg has to be non-zero)
20 **  2) REISERFS_IOC_[GS]ETFLAGS, REISERFS_IOC_[GS]ETVERSION
21 **  3) That's all for a while ...
22 */
23 int reiserfs_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
24                    unsigned long arg)
25 {
26         unsigned int flags;
27
28         switch (cmd) {
29         case REISERFS_IOC_UNPACK:
30                 if (S_ISREG(inode->i_mode)) {
31                         if (arg)
32                                 return reiserfs_unpack(inode, filp);
33                         else
34                                 return 0;
35                 } else
36                         return -ENOTTY;
37                 /* following two cases are taken from fs/ext2/ioctl.c by Remy
38                    Card (card@masi.ibp.fr) */
39         case REISERFS_IOC_GETFLAGS:
40                 if (!reiserfs_attrs(inode->i_sb))
41                         return -ENOTTY;
42
43                 flags = REISERFS_I(inode)->i_attrs;
44                 i_attrs_to_sd_attrs(inode, (__u16 *) & flags);
45                 return put_user(flags, (int __user *)arg);
46         case REISERFS_IOC_SETFLAGS:{
47                         if (!reiserfs_attrs(inode->i_sb))
48                                 return -ENOTTY;
49
50                         if (IS_RDONLY(inode))
51                                 return -EROFS;
52
53                         if ((current->fsuid != inode->i_uid)
54                             && !capable(CAP_FOWNER))
55                                 return -EPERM;
56
57                         if (get_user(flags, (int __user *)arg))
58                                 return -EFAULT;
59
60                         if (((flags ^ REISERFS_I(inode)->
61                               i_attrs) & (REISERFS_IMMUTABLE_FL |
62                                           REISERFS_APPEND_FL))
63                             && !capable(CAP_LINUX_IMMUTABLE))
64                                 return -EPERM;
65
66                         if ((flags & REISERFS_NOTAIL_FL) &&
67                             S_ISREG(inode->i_mode)) {
68                                 int result;
69
70                                 result = reiserfs_unpack(inode, filp);
71                                 if (result)
72                                         return result;
73                         }
74                         sd_attrs_to_i_attrs(flags, inode);
75                         REISERFS_I(inode)->i_attrs = flags;
76                         inode->i_ctime = CURRENT_TIME_SEC;
77                         mark_inode_dirty(inode);
78                         return 0;
79                 }
80         case REISERFS_IOC_GETVERSION:
81                 return put_user(inode->i_generation, (int __user *)arg);
82         case REISERFS_IOC_SETVERSION:
83                 if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
84                         return -EPERM;
85                 if (IS_RDONLY(inode))
86                         return -EROFS;
87                 if (get_user(inode->i_generation, (int __user *)arg))
88                         return -EFAULT;
89                 inode->i_ctime = CURRENT_TIME_SEC;
90                 mark_inode_dirty(inode);
91                 return 0;
92         default:
93                 return -ENOTTY;
94         }
95 }
96
97 /*
98 ** reiserfs_unpack
99 ** Function try to convert tail from direct item into indirect.
100 ** It set up nopack attribute in the REISERFS_I(inode)->nopack
101 */
102 static int reiserfs_unpack(struct inode *inode, struct file *filp)
103 {
104         int retval = 0;
105         int index;
106         struct page *page;
107         struct address_space *mapping;
108         unsigned long write_from;
109         unsigned long blocksize = inode->i_sb->s_blocksize;
110
111         if (inode->i_size == 0) {
112                 REISERFS_I(inode)->i_flags |= i_nopack_mask;
113                 return 0;
114         }
115         /* ioctl already done */
116         if (REISERFS_I(inode)->i_flags & i_nopack_mask) {
117                 return 0;
118         }
119
120         /* we need to make sure nobody is changing the file size beneath
121          ** us
122          */
123         mutex_lock(&inode->i_mutex);
124         reiserfs_write_lock(inode->i_sb);
125
126         write_from = inode->i_size & (blocksize - 1);
127         /* if we are on a block boundary, we are already unpacked.  */
128         if (write_from == 0) {
129                 REISERFS_I(inode)->i_flags |= i_nopack_mask;
130                 goto out;
131         }
132
133         /* we unpack by finding the page with the tail, and calling
134          ** reiserfs_prepare_write on that page.  This will force a 
135          ** reiserfs_get_block to unpack the tail for us.
136          */
137         index = inode->i_size >> PAGE_CACHE_SHIFT;
138         mapping = inode->i_mapping;
139         page = grab_cache_page(mapping, index);
140         retval = -ENOMEM;
141         if (!page) {
142                 goto out;
143         }
144         retval =
145             mapping->a_ops->prepare_write(NULL, page, write_from, write_from);
146         if (retval)
147                 goto out_unlock;
148
149         /* conversion can change page contents, must flush */
150         flush_dcache_page(page);
151         retval =
152             mapping->a_ops->commit_write(NULL, page, write_from, write_from);
153         REISERFS_I(inode)->i_flags |= i_nopack_mask;
154
155       out_unlock:
156         unlock_page(page);
157         page_cache_release(page);
158
159       out:
160         mutex_unlock(&inode->i_mutex);
161         reiserfs_write_unlock(inode->i_sb);
162         return retval;
163 }