Hello,
here is the sixth iteration of my patches to improve filesystem freezing.
The change since last iteration is that filesystem can be frozen with open but
unlinked files. After some thinking, I''ve decided that the best way to
handle
this is to block removal inside ->evict_inode() of each filesystem and use
fs-internal level of freeze protection for that (usually I''ve
instrumented
filesystem''s transaction system to use freeze protection). Handling
inside VFS would be less work but the only level of freeze protection that
has a chance of not causing deadlocks is the one used for page faults and even
there it''s not clear lock ordering would be correct wrt some
fs-specific locks.
I''ve converted ext2, ext4, btrfs, xfs, nilfs2, ocfs2, gfs2 and also
checked
that ext3, reiserfs, jfs should work as well (they have their internal freeze
protection mechanisms, possibly they could be replaced by a generic one but
given these are mostly aging filesystems, it''s not a real priority
IHMO).
So finally I''m not aware of any pending issue with this patch set so if
you
have some concern, please speak up!
Introductory text to first time readers:
Filesystem freezing is currently racy and thus we can end up with dirty data on
frozen filesystem (see changelog patch 13 for detailed race description). This
patch series aims at fixing this.
To be able to block all places where inodes get dirtied, I''ve moved
filesystem
file_update_time() call to ->page_mkwrite callback (patches 01-07) and put
freeze handling in mnt_want_write() / mnt_drop_write(). That however required
some code shuffling and changes to kern_path_create() (see patches 09-12). I
think the result is OK but opinions may differ ;). The advantage of this change
also is that all filesystems get freeze protection almost for free - even ext2
can handle freezing well now.
Another potential contention point might be patch 19. In that patch we make
freeze_super() refuse to freeze the filesystem when there are open but unlinked
files which may be impractical in some cases. The main reason for this is the
problem with handling of file deletion from fput() called with mmap_sem held
(e.g. from munmap(2)), and then there''s the fact that we cannot really
force
such filesystem into a consistent state... But if people think that freezing
with open but unlinked files should happen, then I have some possible
solutions in mind (maybe as a separate patchset since this is large enough).
I''m not able to hit any deadlocks, lockdep warnings, or dirty data on
frozen
filesystem despite beating it with fsstress and bash-shared-mapping while
freezing and unfreezing for several hours (using ext4 and xfs) so I''m
reasonably confident this could finally be the right solution.
Changes since v5:
* handle unlinked & open files on frozen filesystem
* lockdep keys for freeze protection are now per filesystem type
* taught lockdep that freeze protection at lower level does not create
dependency when we already hold freeze protection at higher level
* rebased on 3.5-rc1-ish
Changes since v4:
* added a couple of Acked-by''s
* added some comments & doc update
* added patches from series "Push file_update_time() into
.page_mkwrite"
since it doesn''t make much sense to keep them separate anymore
* rebased on top of 3.4-rc2
Changes since v3:
* added third level of freezing for fs internal purposes - hooked some
filesystems to use it (XFS, nilfs2)
* removed racy i_size check from filemap_mkwrite()
Changes since v2:
* completely rewritten
* freezing is now blocked at VFS entry points
* two stage freezing to handle both mmapped writes and other IO
The biggest changes since v1:
* have two counters to provide safe state transitions for SB_FREEZE_WRITE
and SB_FREEZE_TRANS states
* use percpu counters instead of own percpu structure
* added documentation fixes from the old fs freezing series
* converted XFS to use SB_FREEZE_TRANS counter instead of its private
m_active_trans counter
Honza
CC: Alex Elder <elder@kernel.org>
CC: Anton Altaparmakov <anton@tuxera.com>
CC: Ben Myers <bpm@sgi.com>
CC: Chris Mason <chris.mason@oracle.com>
CC: cluster-devel@redhat.com
CC: "David S. Miller" <davem@davemloft.net>
CC: fuse-devel@lists.sourceforge.net
CC: "J. Bruce Fields" <bfields@fieldses.org>
CC: Joel Becker <jlbec@evilplan.org>
CC: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
CC: linux-btrfs@vger.kernel.org
CC: linux-ext4@vger.kernel.org
CC: linux-nfs@vger.kernel.org
CC: linux-nilfs@vger.kernel.org
CC: linux-ntfs-dev@lists.sourceforge.net
CC: Mark Fasheh <mfasheh@suse.com>
CC: Miklos Szeredi <miklos@szeredi.hu>
CC: ocfs2-devel@oss.oracle.com
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: Steven Whitehouse <swhiteho@redhat.com>
CC: "Theodore Ts''o" <tytso@mit.edu>
CC: xfs@oss.sgi.com
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Jan Kara
2012-Jun-01 22:30 UTC
[Ocfs2-devel] [PATCH 09/27] fs: Push mnt_want_write() outside of i_mutex
Currently, mnt_want_write() is sometimes called with i_mutex held and sometimes
without it. This isn't really a problem because mnt_want_write() is a
non-blocking operation (essentially has a trylock semantics) but when the
function starts to handle also frozen filesystems, it will get a full lock
semantics and thus proper lock ordering has to be established. So move
all mnt_want_write() calls outside of i_mutex.
One non-trivial case needing conversion is kern_path_create() /
user_path_create() which didn't include mnt_want_write() but now needs to
because it acquires i_mutex. Because there are virtual file systems which
don't bother with freeze / remount-ro protection we actually provide both
versions of the function - one which calls mnt_want_write() and one which does
not.
CC: ocfs2-devel at oss.oracle.com
CC: Mark Fasheh <mfasheh at suse.com>
CC: Joel Becker <jlbec at evilplan.org>
CC: "David S. Miller" <davem at davemloft.net>
BugLink: https://bugs.launchpad.net/bugs/897421
Tested-by: Kamal Mostafa <kamal at canonical.com>
Tested-by: Peter M. Petrakis <peter.petrakis at canonical.com>
Tested-by: Dann Frazier <dann.frazier at canonical.com>
Tested-by: Massimo Morana <massimo.morana at canonical.com>
Acked-by: Joel Becker <jlbec at evilplan.org>
Signed-off-by: Jan Kara <jack at suse.cz>
---
fs/namei.c | 115 +++++++++++++++++++++++++++--------------------
fs/ocfs2/refcounttree.c | 10 +---
include/linux/namei.h | 2 +
net/unix/af_unix.c | 13 ++----
4 files changed, 74 insertions(+), 66 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index c651f02..626e620 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2458,7 +2458,9 @@ struct file *do_file_open_root(struct dentry *dentry,
struct vfsmount *mnt,
return file;
}
-struct dentry *kern_path_create(int dfd, const char *pathname, struct path
*path, int is_dir)
+static struct dentry *do_kern_path_create(int dfd, const char *pathname,
+ struct path *path, int is_dir,
+ int freeze_protect)
{
struct dentry *dentry = ERR_PTR(-EEXIST);
struct nameidata nd;
@@ -2476,6 +2478,14 @@ struct dentry *kern_path_create(int dfd, const char
*pathname, struct path *path
nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
nd.intent.open.flags = O_EXCL;
+ if (freeze_protect) {
+ error = mnt_want_write(nd.path.mnt);
+ if (error) {
+ dentry = ERR_PTR(error);
+ goto out;
+ }
+ }
+
/*
* Do the final lookup.
*/
@@ -2504,24 +2514,49 @@ eexist:
dentry = ERR_PTR(-EEXIST);
fail:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ if (freeze_protect)
+ mnt_drop_write(nd.path.mnt);
out:
path_put(&nd.path);
return dentry;
}
+
+struct dentry *kern_path_create(int dfd, const char *pathname, struct path
*path, int is_dir)
+{
+ return do_kern_path_create(dfd, pathname, path, is_dir, 0);
+}
EXPORT_SYMBOL(kern_path_create);
+struct dentry *kern_path_create_thawed(int dfd, const char *pathname, struct
path *path, int is_dir)
+{
+ return do_kern_path_create(dfd, pathname, path, is_dir, 1);
+}
+EXPORT_SYMBOL(kern_path_create_thawed);
+
struct dentry *user_path_create(int dfd, const char __user *pathname, struct
path *path, int is_dir)
{
char *tmp = getname(pathname);
struct dentry *res;
if (IS_ERR(tmp))
return ERR_CAST(tmp);
- res = kern_path_create(dfd, tmp, path, is_dir);
+ res = do_kern_path_create(dfd, tmp, path, is_dir, 0);
putname(tmp);
return res;
}
EXPORT_SYMBOL(user_path_create);
+struct dentry *user_path_create_thawed(int dfd, const char __user *pathname,
struct path *path, int is_dir)
+{
+ char *tmp = getname(pathname);
+ struct dentry *res;
+ if (IS_ERR(tmp))
+ return ERR_CAST(tmp);
+ res = do_kern_path_create(dfd, tmp, path, is_dir, 1);
+ putname(tmp);
+ return res;
+}
+EXPORT_SYMBOL(user_path_create_thawed);
+
int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t
dev)
{
int error = may_create(dir, dentry);
@@ -2576,7 +2611,7 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *,
filename, umode_t, mode,
if (S_ISDIR(mode))
return -EPERM;
- dentry = user_path_create(dfd, filename, &path, 0);
+ dentry = user_path_create_thawed(dfd, filename, &path, 0);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
@@ -2585,12 +2620,9 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *,
filename, umode_t, mode,
error = may_mknod(mode);
if (error)
goto out_dput;
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_mknod(&path, dentry, mode, dev);
if (error)
- goto out_drop_write;
+ goto out_dput;
switch (mode & S_IFMT) {
case 0: case S_IFREG:
error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
@@ -2603,11 +2635,10 @@ SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *,
filename, umode_t, mode,
error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
break;
}
-out_drop_write:
- mnt_drop_write(path.mnt);
out_dput:
dput(dentry);
mutex_unlock(&path.dentry->d_inode->i_mutex);
+ mnt_drop_write(path.mnt);
path_put(&path);
return error;
@@ -2649,24 +2680,20 @@ SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *,
pathname, umode_t, mode)
struct path path;
int error;
- dentry = user_path_create(dfd, pathname, &path, 1);
+ dentry = user_path_create_thawed(dfd, pathname, &path, 1);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
if (!IS_POSIXACL(path.dentry->d_inode))
mode &= ~current_umask();
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_mkdir(&path, dentry, mode);
if (error)
- goto out_drop_write;
+ goto out_dput;
error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
-out_drop_write:
- mnt_drop_write(path.mnt);
out_dput:
dput(dentry);
mutex_unlock(&path.dentry->d_inode->i_mutex);
+ mnt_drop_write(path.mnt);
path_put(&path);
return error;
}
@@ -2761,6 +2788,9 @@ static long do_rmdir(int dfd, const char __user *pathname)
}
nd.flags &= ~LOOKUP_PARENT;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit1;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex,
I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
@@ -2771,19 +2801,15 @@ static long do_rmdir(int dfd, const char __user
*pathname)
error = -ENOENT;
goto exit3;
}
- error = mnt_want_write(nd.path.mnt);
- if (error)
- goto exit3;
error = security_path_rmdir(&nd.path, dentry);
if (error)
- goto exit4;
+ goto exit3;
error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
-exit4:
- mnt_drop_write(nd.path.mnt);
exit3:
dput(dentry);
exit2:
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ mnt_drop_write(nd.path.mnt);
exit1:
path_put(&nd.path);
putname(name);
@@ -2850,6 +2876,9 @@ static long do_unlinkat(int dfd, const char __user
*pathname)
goto exit1;
nd.flags &= ~LOOKUP_PARENT;
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit1;
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex,
I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
@@ -2862,21 +2891,17 @@ static long do_unlinkat(int dfd, const char __user
*pathname)
if (!inode)
goto slashes;
ihold(inode);
- error = mnt_want_write(nd.path.mnt);
- if (error)
- goto exit2;
error = security_path_unlink(&nd.path, dentry);
if (error)
- goto exit3;
+ goto exit2;
error = vfs_unlink(nd.path.dentry->d_inode, dentry);
-exit3:
- mnt_drop_write(nd.path.mnt);
- exit2:
+exit2:
dput(dentry);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
if (inode)
iput(inode); /* truncate the inode here */
+ mnt_drop_write(nd.path.mnt);
exit1:
path_put(&nd.path);
putname(name);
@@ -2936,23 +2961,19 @@ SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
if (IS_ERR(from))
return PTR_ERR(from);
- dentry = user_path_create(newdfd, newname, &path, 0);
+ dentry = user_path_create_thawed(newdfd, newname, &path, 0);
error = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_putname;
- error = mnt_want_write(path.mnt);
- if (error)
- goto out_dput;
error = security_path_symlink(&path, dentry, from);
if (error)
- goto out_drop_write;
+ goto out_dput;
error = vfs_symlink(path.dentry->d_inode, dentry, from);
-out_drop_write:
- mnt_drop_write(path.mnt);
out_dput:
dput(dentry);
mutex_unlock(&path.dentry->d_inode->i_mutex);
+ mnt_drop_write(path.mnt);
path_put(&path);
out_putname:
putname(from);
@@ -3045,7 +3066,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *,
oldname,
if (error)
return error;
- new_dentry = user_path_create(newdfd, newname, &new_path, 0);
+ new_dentry = user_path_create_thawed(newdfd, newname, &new_path, 0);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry))
goto out;
@@ -3053,18 +3074,14 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user
*, oldname,
error = -EXDEV;
if (old_path.mnt != new_path.mnt)
goto out_dput;
- error = mnt_want_write(new_path.mnt);
- if (error)
- goto out_dput;
error = security_path_link(old_path.dentry, &new_path, new_dentry);
if (error)
- goto out_drop_write;
+ goto out_dput;
error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
-out_drop_write:
- mnt_drop_write(new_path.mnt);
out_dput:
dput(new_dentry);
mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+ mnt_drop_write(new_path.mnt);
path_put(&new_path);
out:
path_put(&old_path);
@@ -3261,6 +3278,10 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user
*, oldname,
if (newnd.last_type != LAST_NORM)
goto exit2;
+ error = mnt_want_write(oldnd.path.mnt);
+ if (error)
+ goto exit2;
+
oldnd.flags &= ~LOOKUP_PARENT;
newnd.flags &= ~LOOKUP_PARENT;
newnd.flags |= LOOKUP_RENAME_TARGET;
@@ -3296,23 +3317,19 @@ SYSCALL_DEFINE4(renameat, int, olddfd, const char __user
*, oldname,
if (new_dentry == trap)
goto exit5;
- error = mnt_want_write(oldnd.path.mnt);
- if (error)
- goto exit5;
error = security_path_rename(&oldnd.path, old_dentry,
&newnd.path, new_dentry);
if (error)
- goto exit6;
+ goto exit5;
error = vfs_rename(old_dir->d_inode, old_dentry,
new_dir->d_inode, new_dentry);
-exit6:
- mnt_drop_write(oldnd.path.mnt);
exit5:
dput(new_dentry);
exit4:
dput(old_dentry);
exit3:
unlock_rename(new_dir, old_dir);
+ mnt_drop_write(oldnd.path.mnt);
exit2:
path_put(&newnd.path);
putname(to);
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 9f32d7c..dd0c588 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4453,7 +4453,7 @@ int ocfs2_reflink_ioctl(struct inode *inode,
return error;
}
- new_dentry = user_path_create(AT_FDCWD, newname, &new_path, 0);
+ new_dentry = user_path_create_thawed(AT_FDCWD, newname, &new_path, 0);
error = PTR_ERR(new_dentry);
if (IS_ERR(new_dentry)) {
mlog_errno(error);
@@ -4466,19 +4466,13 @@ int ocfs2_reflink_ioctl(struct inode *inode,
goto out_dput;
}
- error = mnt_want_write(new_path.mnt);
- if (error) {
- mlog_errno(error);
- goto out_dput;
- }
-
error = ocfs2_vfs_reflink(old_path.dentry,
new_path.dentry->d_inode,
new_dentry, preserve);
- mnt_drop_write(new_path.mnt);
out_dput:
dput(new_dentry);
mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+ mnt_drop_write(new_path.mnt);
path_put(&new_path);
out:
path_put(&old_path);
diff --git a/include/linux/namei.h b/include/linux/namei.h
index ffc0213..432f6bb 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -77,7 +77,9 @@ extern int user_path_at_empty(int, const char __user *,
unsigned, struct path *,
extern int kern_path(const char *, unsigned, struct path *);
extern struct dentry *kern_path_create(int, const char *, struct path *, int);
+extern struct dentry *kern_path_create_thawed(int, const char *, struct path *,
int);
extern struct dentry *user_path_create(int, const char __user *, struct path *,
int);
+extern struct dentry *user_path_create_thawed(int, const char __user *, struct
path *, int);
extern int kern_path_parent(const char *, struct nameidata *);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 641f2e4..37e65a2 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -866,7 +866,7 @@ static int unix_bind(struct socket *sock, struct sockaddr
*uaddr, int addr_len)
* Get the parent directory, calculate the hash for last
* component.
*/
- dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
+ dentry = kern_path_create_thawed(AT_FDCWD, sun_path, &path, 0);
err = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_mknod_parent;
@@ -876,19 +876,13 @@ static int unix_bind(struct socket *sock, struct sockaddr
*uaddr, int addr_len)
*/
mode = S_IFSOCK |
(SOCK_INODE(sock)->i_mode & ~current_umask());
- err = mnt_want_write(path.mnt);
- if (err)
- goto out_mknod_dput;
err = security_path_mknod(&path, dentry, mode, 0);
if (err)
- goto out_mknod_drop_write;
- err = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
-out_mknod_drop_write:
- mnt_drop_write(path.mnt);
- if (err)
goto out_mknod_dput;
+ err = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
mutex_unlock(&path.dentry->d_inode->i_mutex);
dput(path.dentry);
+ mnt_drop_write(path.mnt);
path.dentry = dentry;
addr->hash = UNIX_HASH_SIZE;
@@ -925,6 +919,7 @@ out:
out_mknod_dput:
dput(dentry);
mutex_unlock(&path.dentry->d_inode->i_mutex);
+ mnt_drop_write(path.mnt);
path_put(&path);
out_mknod_parent:
if (err == -EEXIST)
--
1.7.1
Jan Kara
2012-Jun-01 22:30 UTC
[PATCH 11/27] btrfs: Push mnt_want_write() outside of i_mutex
When mnt_want_write() starts to handle freezing it will get a full lock semantics requiring proper lock ordering. So push mnt_want_write() call consistently outside of i_mutex. CC: Chris Mason <chris.mason@oracle.com> CC: linux-btrfs@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> --- fs/btrfs/ioctl.c | 23 +++++++++++------------ 1 files changed, 11 insertions(+), 12 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 24b776c..440655b 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -192,6 +192,10 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg) if (!inode_owner_or_capable(inode)) return -EACCES; + ret = mnt_want_write_file(file); + if (ret) + return ret; + mutex_lock(&inode->i_mutex); ip_oldflags = ip->flags; @@ -206,10 +210,6 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg) } } - ret = mnt_want_write_file(file); - if (ret) - goto out_unlock; - if (flags & FS_SYNC_FL) ip->flags |= BTRFS_INODE_SYNC; else @@ -272,9 +272,9 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg) inode->i_flags = i_oldflags; } - mnt_drop_write_file(file); out_unlock: mutex_unlock(&inode->i_mutex); + mnt_drop_write_file(file); return ret; } @@ -640,6 +640,10 @@ static noinline int btrfs_mksubvol(struct path *parent, struct dentry *dentry; int error; + error = mnt_want_write(parent->mnt); + if (error) + return error; + mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT); dentry = lookup_one_len(name, parent->dentry, namelen); @@ -651,13 +655,9 @@ static noinline int btrfs_mksubvol(struct path *parent, if (dentry->d_inode) goto out_dput; - error = mnt_want_write(parent->mnt); - if (error) - goto out_dput; - error = btrfs_may_create(dir, dentry); if (error) - goto out_drop_write; + goto out_dput; down_read(&BTRFS_I(dir)->root->fs_info->subvol_sem); @@ -675,12 +675,11 @@ static noinline int btrfs_mksubvol(struct path *parent, fsnotify_mkdir(dir, dentry); out_up_read: up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem); -out_drop_write: - mnt_drop_write(parent->mnt); out_dput: dput(dentry); out_unlock: mutex_unlock(&dir->i_mutex); + mnt_drop_write(parent->mnt); return error; } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Jan Kara
2012-Jun-01 22:30 UTC
[Ocfs2-devel] [PATCH 19/27] ocfs2: Convert to new freezing mechanism
Protect ocfs2_page_mkwrite() and ocfs2_file_aio_write() using the new freeze
protection. We also protect several ioctl entry points which were missing the
protection. Finally, we add freeze protection to the journaling mechanism so
that iput() of unlinked inode cannot modify a frozen filesystem.
CC: Mark Fasheh <mfasheh at suse.com>
CC: Joel Becker <jlbec at evilplan.org>
CC: ocfs2-devel at oss.oracle.com
Acked-by: Joel Becker <jlbec at evilplan.org>
Signed-off-by: Jan Kara <jack at suse.cz>
---
fs/ocfs2/file.c | 11 +++++++++--
fs/ocfs2/ioctl.c | 14 ++++++++++++--
fs/ocfs2/journal.c | 7 ++++++-
fs/ocfs2/mmap.c | 2 ++
4 files changed, 29 insertions(+), 5 deletions(-)
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 061591a..9b1e3d4 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1971,6 +1971,7 @@ int ocfs2_change_file_space(struct file *file, unsigned
int cmd,
{
struct inode *inode = file->f_path.dentry->d_inode;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+ int ret;
if ((cmd == OCFS2_IOC_RESVSP || cmd == OCFS2_IOC_RESVSP64) &&
!ocfs2_writes_unwritten_extents(osb))
@@ -1985,7 +1986,12 @@ int ocfs2_change_file_space(struct file *file, unsigned
int cmd,
if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
- return __ocfs2_change_file_space(file, inode, file->f_pos, cmd, sr, 0);
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+ ret = __ocfs2_change_file_space(file, inode, file->f_pos, cmd, sr, 0);
+ mnt_drop_write_file(file);
+ return ret;
}
static long ocfs2_fallocate(struct file *file, int mode, loff_t offset,
@@ -2261,7 +2267,7 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
if (iocb->ki_left == 0)
return 0;
- vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+ sb_start_write(inode->i_sb);
appending = file->f_flags & O_APPEND ? 1 : 0;
direct_io = file->f_flags & O_DIRECT ? 1 : 0;
@@ -2434,6 +2440,7 @@ out_sems:
ocfs2_iocb_clear_sem_locked(iocb);
mutex_unlock(&inode->i_mutex);
+ sb_end_write(inode->i_sb);
if (written)
ret = written;
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index a1a1bfd..d9c352b 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -926,7 +926,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
if (get_user(new_clusters, (int __user *)arg))
return -EFAULT;
- return ocfs2_group_extend(inode, new_clusters);
+ status = mnt_want_write_file(filp);
+ if (status)
+ return status;
+ status = ocfs2_group_extend(inode, new_clusters);
+ mnt_drop_write_file(filp);
+ return status;
case OCFS2_IOC_GROUP_ADD:
case OCFS2_IOC_GROUP_ADD64:
if (!capable(CAP_SYS_RESOURCE))
@@ -935,7 +940,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
if (copy_from_user(&input, (int __user *) arg, sizeof(input)))
return -EFAULT;
- return ocfs2_group_add(inode, &input);
+ status = mnt_want_write_file(filp);
+ if (status)
+ return status;
+ status = ocfs2_group_add(inode, &input);
+ mnt_drop_write_file(filp);
+ return status;
case OCFS2_IOC_REFLINK:
if (copy_from_user(&args, (struct reflink_arguments *)arg,
sizeof(args)))
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 0a42ae9..2dd36af 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -355,11 +355,14 @@ handle_t *ocfs2_start_trans(struct ocfs2_super *osb, int
max_buffs)
if (journal_current_handle())
return jbd2_journal_start(journal, max_buffs);
+ sb_start_intwrite(osb->sb);
+
down_read(&osb->journal->j_trans_barrier);
handle = jbd2_journal_start(journal, max_buffs);
if (IS_ERR(handle)) {
up_read(&osb->journal->j_trans_barrier);
+ sb_end_intwrite(osb->sb);
mlog_errno(PTR_ERR(handle));
@@ -388,8 +391,10 @@ int ocfs2_commit_trans(struct ocfs2_super *osb,
if (ret < 0)
mlog_errno(ret);
- if (!nested)
+ if (!nested) {
up_read(&journal->j_trans_barrier);
+ sb_end_intwrite(osb->sb);
+ }
return ret;
}
diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index 9cd4108..d150372 100644
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -136,6 +136,7 @@ static int ocfs2_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
sigset_t oldset;
int ret;
+ sb_start_pagefault(inode->i_sb);
ocfs2_block_signals(&oldset);
/*
@@ -165,6 +166,7 @@ static int ocfs2_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
out:
ocfs2_unblock_signals(&oldset);
+ sb_end_pagefault(inode->i_sb);
return ret;
}
--
1.7.1
We convert btrfs_file_aio_write() to use new freeze check. We also add proper
freeze protection to btrfs_page_mkwrite(). We also add freeze protection to
the transaction mechanism to avoid starting transactions on frozen filesystem.
At minimum this is necessary to stop iput() of unlinked file to change frozen
filesystem during truncation.
Checks in cleaner_kthread() and transaction_kthread() can be safely removed
since btrfs_freeze() will lock the mutexes and thus block the threads (and they
shouldn''t have anything to do anyway).
CC: linux-btrfs@vger.kernel.org
CC: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/btrfs/disk-io.c | 3 ---
fs/btrfs/file.c | 3 ++-
fs/btrfs/inode.c | 6 +++++-
fs/btrfs/transaction.c | 7 +++++++
4 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7ae51de..663f3a0 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1532,8 +1532,6 @@ static int cleaner_kthread(void *arg)
struct btrfs_root *root = arg;
do {
- vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
-
if (!(root->fs_info->sb->s_flags & MS_RDONLY) &&
mutex_trylock(&root->fs_info->cleaner_mutex)) {
btrfs_run_delayed_iputs(root);
@@ -1565,7 +1563,6 @@ static int transaction_kthread(void *arg)
do {
cannot_commit = false;
delay = HZ * 30;
- vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE);
mutex_lock(&root->fs_info->transaction_kthread_mutex);
spin_lock(&root->fs_info->trans_lock);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 876cddd..7f3d7fe 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1392,7 +1392,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
ssize_t err = 0;
size_t count, ocount;
- vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
+ sb_start_write(inode->i_sb);
mutex_lock(&inode->i_mutex);
@@ -1482,6 +1482,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
num_written = err;
}
out:
+ sb_end_write(inode->i_sb);
current->backing_dev_info = NULL;
return num_written ? num_written : err;
}
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e9991ad..54e5378 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6563,6 +6563,7 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct
vm_fault *vmf)
u64 page_start;
u64 page_end;
+ sb_start_pagefault(inode->i_sb);
ret = btrfs_delalloc_reserve_space(inode, PAGE_CACHE_SIZE);
if (!ret) {
ret = btrfs_update_time(vma->vm_file);
@@ -6652,12 +6653,15 @@ again:
unlock_extent_cached(io_tree, page_start, page_end, &cached_state,
GFP_NOFS);
out_unlock:
- if (!ret)
+ if (!ret) {
+ sb_end_pagefault(inode->i_sb);
return VM_FAULT_LOCKED;
+ }
unlock_page(page);
out:
btrfs_delalloc_release_space(inode, PAGE_CACHE_SIZE);
out_noreserve:
+ sb_end_pagefault(inode->i_sb);
return ret;
}
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 1791c6e..05d8c29 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -325,6 +325,8 @@ again:
if (!h)
return ERR_PTR(-ENOMEM);
+ sb_start_intwrite(root->fs_info->sb);
+
if (may_wait_transaction(root, type))
wait_current_trans(root);
@@ -335,6 +337,7 @@ again:
} while (ret == -EBUSY);
if (ret < 0) {
+ sb_end_intwrite(root->fs_info->sb);
kmem_cache_free(btrfs_trans_handle_cachep, h);
return ERR_PTR(ret);
}
@@ -524,6 +527,8 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle
*trans,
count++;
}
+ sb_end_intwrite(root->fs_info->sb);
+
if (lock && !atomic_read(&root->fs_info->open_ioctl_trans)
&&
should_end_transaction(trans, root)) {
trans->transaction->blocked = 1;
@@ -1507,6 +1512,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle
*trans,
put_transaction(cur_trans);
put_transaction(cur_trans);
+ sb_end_intwrite(root->fs_info->sb);
+
trace_btrfs_transaction_commit(root);
btrfs_scrub_continue(root);
--
1.7.1
--
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Al Viro
2012-Jun-09 06:29 UTC
[Ocfs2-devel] [PATCH 00/27 v6] Fix filesystem freezing deadlocks
On Sat, Jun 02, 2012 at 12:30:14AM +0200, Jan Kara wrote:> Hello, > > here is the sixth iteration of my patches to improve filesystem freezing. > The change since last iteration is that filesystem can be frozen with open but > unlinked files. After some thinking, I've decided that the best way to handle > this is to block removal inside ->evict_inode() of each filesystem and use > fs-internal level of freeze protection for that (usually I've instrumented > filesystem's transaction system to use freeze protection). Handling > inside VFS would be less work but the only level of freeze protection that > has a chance of not causing deadlocks is the one used for page faults and even > there it's not clear lock ordering would be correct wrt some fs-specific locks. > I've converted ext2, ext4, btrfs, xfs, nilfs2, ocfs2, gfs2 and also checked > that ext3, reiserfs, jfs should work as well (they have their internal freeze > protection mechanisms, possibly they could be replaced by a generic one but > given these are mostly aging filesystems, it's not a real priority IHMO). > So finally I'm not aware of any pending issue with this patch set so if you > have some concern, please speak up!Could you rebase on top of e.g. -rc2 and repost?