Hello Jan, tried on 3.7-rc4, works great! thanks!
will You submit as-is, or do You plan any further changes? do You plan to backport for stable kernels? I can try it and send for review if You want (although we'll have to wait till it's upstream anyways) cheers nik On Wed, Nov 07, 2012 at 07:51:37PM +0100, Jan Kara wrote: > On Thu 01-11-12 23:50:53, Jan Kara wrote: > > On Thu 01-11-12 15:23:25, Nikola Ciprich wrote: > > > Nov 1 14:23:25 vmnci22 [ 1075.178123] SysRq : Show Blocked State > > > Nov 1 14:23:25 vmnci22 [ 1075.180555] task PC > > > stack pid father > > > Nov 1 14:23:25 vmnci22 [ 1075.180592] fsfreeze D 0000000000000000 > > > 0 4215 4195 0x00000000 > > > Nov 1 14:23:25 vmnci22 [ 1075.180599] ffff8800090b9b28 0000000000000046 > > > 0000000000000000 ffffffff00000000 > > > Nov 1 14:23:25 vmnci22 [ 1075.180606] 0000000000013780 ffff8800090b9fd8 > > > ffff88000f716170 ffff88000f715e80 > > > Nov 1 14:23:25 vmnci22 [ 1075.180612] ffff88000f715dc0 ffffffff81566080 > > > ffff88000f716170 000000010002f405 > > > Nov 1 14:23:25 vmnci22 [ 1075.180619] Call Trace: > > > Nov 1 14:23:25 vmnci22 [ 1075.180693] [<ffffffff810e2dbb>] > > > __generic_file_aio_write+0xbb/0x420 > > > Nov 1 14:23:25 vmnci22 [ 1075.180729] [<ffffffff81079290>] ? > > > autoremove_wake_function+0x0/0x40 > > > Nov 1 14:23:25 vmnci22 [ 1075.180736] [<ffffffff810e317f>] > > > generic_file_aio_write+0x5f/0xc0 > > Thanks. So the system isn't really deadlocked. It's just that fsfreeze > > command hangs, isn't it? OK, I understand that it's kind of incovenient > > situation because every command will hang like this when the filesystem is > > frozen. > > > > Now I only have to come up with a way to improve this... It isn't quite > > simple - to properly protect against freezing be have to communicate down > > into generic_file_aio_write() that we want to bail out if filesystem is > > frozen instead of waiting. > OK, can you test attached patch? > > Honza > > -- > Jan Kara <[email protected]> > SUSE Labs, CR > From 1cc937c5a850b2f9f0c2a83fdf757911602db198 Mon Sep 17 00:00:00 2001 > From: Jan Kara <[email protected]> > Date: Wed, 7 Nov 2012 19:26:45 +0100 > Subject: [PATCH] fs: Fix hang with BSD accounting on frozen filesystem > > When BSD process accounting is enabled and logs information to a filesystem > which gets frozen, system easily becomes unusable because each attempt to > account process information blocks. Thus e.g. every task gets blocked in exit. > > It seems better to drop accounting information (which can already happen when > filesystem is running out of space) instead of locking system up. This is > implemented using a special flag FMODE_NO_FREEZE_WAIT in file->f_mode of a > file to which accounting information is written. > > Signed-off-by: Jan Kara <[email protected]> > --- > fs/btrfs/file.c | 3 ++- > fs/cifs/file.c | 3 ++- > fs/fuse/file.c | 3 ++- > fs/ntfs/file.c | 3 ++- > fs/ocfs2/file.c | 3 ++- > fs/open.c | 2 +- > fs/xfs/xfs_file.c | 3 ++- > include/linux/fs.h | 14 ++++++++++++++ > kernel/acct.c | 1 + > mm/filemap.c | 3 ++- > 10 files changed, 30 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > index 9ab1bed..6eb2e30 100644 > --- a/fs/btrfs/file.c > +++ b/fs/btrfs/file.c > @@ -1411,7 +1411,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, > ssize_t err = 0; > size_t count, ocount; > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > > mutex_lock(&inode->i_mutex); > > diff --git a/fs/cifs/file.c b/fs/cifs/file.c > index edb25b4..1629e47 100644 > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c > @@ -2448,7 +2448,8 @@ cifs_writev(struct kiocb *iocb, const struct iovec *iov, > > BUG_ON(iocb->ki_pos != pos); > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > > /* > * We need to hold the sem to be sure nobody modifies lock list > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index 78d2837..641df9e 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -947,7 +947,8 @@ static ssize_t fuse_file_aio_write(struct kiocb *iocb, > const struct iovec *iov, > return err; > > count = ocount; > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > mutex_lock(&inode->i_mutex); > > /* We can write back this queue in page reclaim */ > diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c > index 1ecf464..028b349 100644 > --- a/fs/ntfs/file.c > +++ b/fs/ntfs/file.c > @@ -2118,7 +2118,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, > const struct iovec *iov, > > BUG_ON(iocb->ki_pos != pos); > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > mutex_lock(&inode->i_mutex); > ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos); > mutex_unlock(&inode->i_mutex); > diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c > index 5a4ee77..93ef34d 100644 > --- a/fs/ocfs2/file.c > +++ b/fs/ocfs2/file.c > @@ -2265,7 +2265,8 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb, > if (iocb->ki_left == 0) > return 0; > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > > appending = file->f_flags & O_APPEND ? 1 : 0; > direct_io = file->f_flags & O_DIRECT ? 1 : 0; > diff --git a/fs/open.c b/fs/open.c > index 59071f5..42bd875 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -808,7 +808,7 @@ static inline int build_open_flags(int flags, umode_t > mode, struct open_flags *o > op->mode = 0; > > /* Must never be set by userspace */ > - flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC; > + flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC & ~FMODE_NO_FREEZE_WAIT; > > /* > * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index aa473fa..7d8af61 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -771,7 +771,8 @@ xfs_file_aio_write( > if (ocount == 0) > return 0; > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > > if (XFS_FORCED_SHUTDOWN(ip->i_mount)) { > ret = -EIO; > diff --git a/include/linux/fs.h b/include/linux/fs.h > index b33cfc9..c040a6c 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -123,6 +123,9 @@ typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t > offset, > /* File was opened by fanotify and shouldn't generate fanotify events */ > #define FMODE_NONOTIFY ((__force fmode_t)0x1000000) > > +/* Write to file should fail on frozen fs rather than block */ > +#define FMODE_NO_FREEZE_WAIT ((__force fmode_t)0x2000000) > + > /* > * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector > * that indicates that they should check the contents of the iovec are > @@ -1401,6 +1404,17 @@ static inline int sb_start_write_trylock(struct > super_block *sb) > return __sb_start_write(sb, SB_FREEZE_WRITE, false); > } > > +/* > + * We use trylock semantics if write originates in kernel and normal lock > + * semantics otherwise. This is a hack but solves problems with deadlocking > + * of e.g. psacct when filesystem is frozen. > + */ > +static inline int sb_start_file_write(struct file *file) > +{ > + return __sb_start_write(file->f_mapping->host->i_sb, SB_FREEZE_WRITE, > + !(file->f_mode & FMODE_NO_FREEZE_WAIT)); > +} > + > /** > * sb_start_pagefault - get write access to a superblock from a page fault > * @sb: the super we write to > diff --git a/kernel/acct.c b/kernel/acct.c > index 051e071..0b5f231 100644 > --- a/kernel/acct.c > +++ b/kernel/acct.c > @@ -183,6 +183,7 @@ static void acct_file_reopen(struct bsd_acct_struct > *acct, struct file *file, > acct->needcheck = jiffies + ACCT_TIMEOUT*HZ; > acct->active = 1; > list_add(&acct->list, &acct_list); > + file->f_mode |= FMODE_NO_FREEZE_WAIT; > } > if (old_acct) { > mnt_unpin(old_acct->f_path.mnt); > diff --git a/mm/filemap.c b/mm/filemap.c > index 83efee7..3b2812b 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2527,7 +2527,8 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, > const struct iovec *iov, > > BUG_ON(iocb->ki_pos != pos); > > - sb_start_write(inode->i_sb); > + if (!sb_start_file_write(file)) > + return -EAGAIN; > mutex_lock(&inode->i_mutex); > ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); > mutex_unlock(&inode->i_mutex); > -- > 1.7.1 > -- ------------------------------------- Ing. Nikola CIPRICH LinuxBox.cz, s.r.o. 28. rijna 168, 709 00 Ostrava tel.: +420 591 166 214 fax: +420 596 621 273 mobil: +420 777 093 799 www.linuxbox.cz mobil servis: +420 737 238 656 email servis: [email protected] -------------------------------------
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