This patch removes BKL protection from the invocation of the
super_operations ->statfs() method, and shifts it into the filesystems
where necessary. Any out-of-tree filesystems may need to take the BKL in
their statfs() methods if they were relying on it for synchronisation.
Several ->statfs() implementation changes in the previous version of the
patch have been dropped following assurances from Oleg Drokin, Anton
Altaparmakov and Matthew Wilcox that they were unnecessary.
All ->statfs() implementations have been modified to take the BKL,
except for the following:
- those that don't reference any external mutable data:
simple_statfs
isofs_statfs
ncp_statfs
cramfs_statfs
romfs_statfs
efs_statfs
vxfs_statfs
ntfs_statfs
adfs_statfs
- those that already have their own locking:
ext2_statfs
shmem_statfs
fat_statfs
UMSDOS_statfs
minix_statfs
sysv_statfs
reiserfs_statfs
affs_statfs
bfs_statfs
ext3_statfs
hfs_statfs
jffs2_statfs
jfs_statfs
Additionally, capifs is changed to use simple_statfs rather than its
own home-grown version.
The BKL change has been flagged at the end of
Documentation/filesystems/porting, along with the recent change to
->permission BKL usage.
Paul
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/Documentation/filesystems/Locking linux-2.5.24-statfs2/Documentation/filesystems/Locking
--- linux-2.5.24/Documentation/filesystems/Locking Tue Jun 18 19:11:52 2002
+++ linux-2.5.24-statfs2/Documentation/filesystems/Locking Wed Jul 3 00:22:36 2002
@@ -108,7 +108,7 @@
clear_inode: no
put_super: yes yes maybe (see below)
write_super: no yes maybe (see below)
-statfs: yes no no
+statfs: no no no
remount_fs: yes yes maybe (see below)
umount_begin: yes no maybe (see below)
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/Documentation/filesystems/porting linux-2.5.24-statfs2/Documentation/filesystems/porting
--- linux-2.5.24/Documentation/filesystems/porting Tue Jun 18 19:11:51 2002
+++ linux-2.5.24-statfs2/Documentation/filesystems/porting Wed Jul 3 00:26:49 2002
@@ -81,7 +81,7 @@
[mandatory]
->lookup(), ->truncate(), ->create(), ->unlink(), ->mknod(), ->mkdir(),
-->rmdir(), ->link(), ->lseek(), ->symlink(), ->rename(), ->permission()
+->rmdir(), ->link(), ->lseek(), ->symlink(), ->rename()
and ->readdir() are called without BKL now. Grab it on entry, drop upon return
- that will guarantee the same locking you used to have. If your method or its
parts do not need BKL - better yet, now you can shift lock_kernel() and
@@ -228,3 +228,19 @@
Use bdev_read_only(bdev) instead of is_read_only(kdev). The latter
is still alive, but only because of the mess in drivers/s390/block/dasd.c.
As soon as it gets fixed is_read_only() will die.
+
+---
+[mandatory]
+
+->permission() is called without BKL now. Grab it on entry, drop upon
+return - that will guarantee the same locking you used to have. If
+your method or its parts do not need BKL - better yet, now you can
+shift lock_kernel() and unlock_kernel() so that they would protect
+exactly what needs to be protected.
+
+---
+[mandatory]
+
+->statfs() is now called without BKL held. BKL should have been
+shifted into individual fs sb_op functions where it's not clear that
+it's safe to remove it. If you don't need it, remove it.
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/drivers/isdn/capi/capifs.c linux-2.5.24-statfs2/drivers/isdn/capi/capifs.c
--- linux-2.5.24/drivers/isdn/capi/capifs.c Tue Jun 18 19:11:50 2002
+++ linux-2.5.24-statfs2/drivers/isdn/capi/capifs.c Wed Jul 3 00:22:36 2002
@@ -221,11 +221,9 @@
kfree(sbi);
}
-static int capifs_statfs(struct super_block *sb, struct statfs *buf);
-
static struct super_operations capifs_sops = {
put_super: capifs_put_super,
- statfs: capifs_statfs,
+ statfs: simple_statfs,
};
static int capifs_parse_options(char *options, struct capifs_sb_info *sbi)
@@ -354,19 +352,6 @@
return -EINVAL;
}
-static int capifs_statfs(struct super_block *sb, struct statfs *buf)
-{
- buf->f_type = CAPIFS_SUPER_MAGIC;
- buf->f_bsize = 1024;
- buf->f_blocks = 0;
- buf->f_bfree = 0;
- buf->f_bavail = 0;
- buf->f_files = 0;
- buf->f_ffree = 0;
- buf->f_namelen = NAME_MAX;
- return 0;
-}
-
static struct inode *capifs_new_inode(struct super_block *sb)
{
struct inode *inode = new_inode(sb);
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/coda/inode.c linux-2.5.24-statfs2/fs/coda/inode.c
--- linux-2.5.24/fs/coda/inode.c Tue Jun 18 19:11:55 2002
+++ linux-2.5.24-statfs2/fs/coda/inode.c Wed Jul 3 00:22:36 2002
@@ -281,9 +281,13 @@
static int coda_statfs(struct super_block *sb, struct statfs *buf)
{
int error;
+
+ lock_kernel();
error = venus_statfs(sb, buf);
+ unlock_kernel();
+
if (error) {
/* fake something like AFS does */
buf->f_blocks = 9000000;
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/ext3/super.c linux-2.5.24-statfs2/fs/ext3/super.c
--- linux-2.5.24/fs/ext3/super.c Tue Jun 18 19:11:58 2002
+++ linux-2.5.24-statfs2/fs/ext3/super.c Wed Jul 3 00:28:00 2002
@@ -504,7 +504,7 @@
write_super: ext3_write_super, /* BKL not held. We take it. Needed? */
write_super_lockfs: ext3_write_super_lockfs, /* BKL not held. Take it */
unlockfs: ext3_unlockfs, /* BKL not held. We take it */
- statfs: ext3_statfs, /* BKL held */
+ statfs: ext3_statfs, /* BKL not held. */
remount_fs: ext3_remount, /* BKL held */
};
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/freevxfs/vxfs_super.c linux-2.5.24-statfs2/fs/freevxfs/vxfs_super.c
--- linux-2.5.24/fs/freevxfs/vxfs_super.c Tue Jun 18 19:11:51 2002
+++ linux-2.5.24-statfs2/fs/freevxfs/vxfs_super.c Wed Jul 3 00:22:36 2002
@@ -98,7 +98,7 @@
* Zero.
*
* Locking:
- * We are under bkl and @sbp->s_lock.
+ * No locks held.
*
* Notes:
* This is everything but complete...
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/hpfs/super.c linux-2.5.24-statfs2/fs/hpfs/super.c
--- linux-2.5.24/fs/hpfs/super.c Tue Jun 18 19:11:56 2002
+++ linux-2.5.24-statfs2/fs/hpfs/super.c Wed Jul 3 00:28:21 2002
@@ -134,6 +134,8 @@
int hpfs_statfs(struct super_block *s, struct statfs *buf)
{
+ lock_kernel();
+
/*if (s->s_hpfs_n_free == -1) {*/
s->s_hpfs_n_free = count_bitmaps(s);
s->s_hpfs_n_free_dnodes = hpfs_count_one_bitmap(s, s->s_hpfs_dmap);
@@ -146,6 +148,9 @@
buf->f_files = s->s_hpfs_dirband_size / 4;
buf->f_ffree = s->s_hpfs_n_free_dnodes;
buf->f_namelen = 254;
+
+ unlock_kernel();
+
return 0;
}
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/jffs/inode-v23.c linux-2.5.24-statfs2/fs/jffs/inode-v23.c
--- linux-2.5.24/fs/jffs/inode-v23.c Tue Jun 18 19:11:56 2002
+++ linux-2.5.24-statfs2/fs/jffs/inode-v23.c Wed Jul 3 00:22:36 2002
@@ -383,7 +383,11 @@
jffs_statfs(struct super_block *sb, struct statfs *buf)
{
struct jffs_control *c = (struct jffs_control *) sb->u.generic_sbp;
- struct jffs_fmcontrol *fmc = c->fmc;
+ struct jffs_fmcontrol *fmc;
+
+ lock_kernel();
+
+ fmc = c->fmc;
D2(printk("jffs_statfs()\n"));
@@ -401,6 +405,9 @@
buf->f_ffree = buf->f_bfree;
/* buf->f_fsid = 0; */
buf->f_namelen = JFFS_MAX_NAME_LEN;
+
+ unlock_kernel();
+
return 0;
}
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/nfs/inode.c linux-2.5.24-statfs2/fs/nfs/inode.c
--- linux-2.5.24/fs/nfs/inode.c Tue Jun 18 19:11:57 2002
+++ linux-2.5.24-statfs2/fs/nfs/inode.c Wed Jul 3 00:28:52 2002
@@ -474,6 +474,8 @@
struct nfs_fsinfo res;
int error;
+ lock_kernel();
+
error = server->rpc_ops->statfs(server, NFS_FH(sb->s_root->d_inode), &res);
buf->f_type = NFS_SUPER_MAGIC;
if (error < 0)
@@ -491,11 +493,17 @@
if (res.namelen == 0 || res.namelen > server->namelen)
res.namelen = server->namelen;
buf->f_namelen = res.namelen;
+
+ out:
+ unlock_kernel();
+
return 0;
+
out_err:
- printk("nfs_statfs: statfs error = %d\n", -error);
+ printk(KERN_WARNING "nfs_statfs: statfs error = %d\n", -error);
buf->f_bsize = buf->f_blocks = buf->f_bfree = buf->f_bavail = -1;
- return 0;
+ goto out;
+
}
static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/open.c linux-2.5.24-statfs2/fs/open.c
--- linux-2.5.24/fs/open.c Tue Jun 18 19:11:46 2002
+++ linux-2.5.24-statfs2/fs/open.c Wed Jul 3 00:22:36 2002
@@ -30,9 +30,7 @@
retval = -ENOSYS;
if (sb->s_op && sb->s_op->statfs) {
memset(buf, 0, sizeof(struct statfs));
- lock_kernel();
retval = sb->s_op->statfs(sb, buf);
- unlock_kernel();
}
}
return retval;
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/qnx4/inode.c linux-2.5.24-statfs2/fs/qnx4/inode.c
--- linux-2.5.24/fs/qnx4/inode.c Tue Jun 18 19:11:52 2002
+++ linux-2.5.24-statfs2/fs/qnx4/inode.c Wed Jul 3 00:29:20 2002
@@ -281,6 +281,8 @@
static int qnx4_statfs(struct super_block *sb, struct statfs *buf)
{
+ lock_kernel();
+
buf->f_type = sb->s_magic;
buf->f_bsize = sb->s_blocksize;
buf->f_blocks = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
@@ -288,6 +290,8 @@
buf->f_bavail = buf->f_bfree;
buf->f_namelen = QNX4_NAME_MAX;
+ unlock_kernel();
+
return 0;
}
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/smbfs/inode.c linux-2.5.24-statfs2/fs/smbfs/inode.c
--- linux-2.5.24/fs/smbfs/inode.c Tue Jun 18 19:11:48 2002
+++ linux-2.5.24-statfs2/fs/smbfs/inode.c Wed Jul 3 00:22:36 2002
@@ -604,7 +604,13 @@
static int
smb_statfs(struct super_block *sb, struct statfs *buf)
{
- int result = smb_proc_dskattr(sb, buf);
+ int result;
+
+ lock_kernel();
+
+ result = smb_proc_dskattr(sb, buf);
+
+ unlock_kernel();
buf->f_type = SMB_SUPER_MAGIC;
buf->f_namelen = SMB_MAXPATHLEN;
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/udf/super.c linux-2.5.24-statfs2/fs/udf/super.c
--- linux-2.5.24/fs/udf/super.c Tue Jun 18 19:11:56 2002
+++ linux-2.5.24-statfs2/fs/udf/super.c Wed Jul 3 00:29:44 2002
@@ -1726,6 +1726,8 @@
static int
udf_statfs(struct super_block *sb, struct statfs *buf)
{
+ lock_kernel();
+
buf->f_type = UDF_SUPER_MAGIC;
buf->f_bsize = sb->s_blocksize;
buf->f_blocks = UDF_SB_PARTLEN(sb, UDF_SB_PARTITION(sb));
@@ -1738,6 +1740,8 @@
/* __kernel_fsid_t f_fsid */
buf->f_namelen = UDF_NAME_LEN;
+ unlock_kernel();
+
return 0;
}
diff -Naur -X /mnt/elbrus/home/pmenage/dontdiff linux-2.5.24/fs/ufs/super.c linux-2.5.24-statfs2/fs/ufs/super.c
--- linux-2.5.24/fs/ufs/super.c Tue Jun 18 19:11:44 2002
+++ linux-2.5.24-statfs2/fs/ufs/super.c Wed Jul 3 00:22:36 2002
@@ -959,6 +959,8 @@
struct ufs_sb_private_info * uspi;
struct ufs_super_block_first * usb1;
+ lock_kernel();
+
uspi = sb->u.ufs_sb.s_uspi;
usb1 = ubh_get_usb_first (USPI_UBH);
@@ -972,6 +974,9 @@
buf->f_files = uspi->s_ncg * uspi->s_ipg;
buf->f_ffree = fs32_to_cpu(sb, usb1->fs_cstotal.cs_nifree);
buf->f_namelen = UFS_MAXNAMLEN;
+
+ unlock_kernel();
+
return 0;
}