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NTFS: Fix a mount time deadlock.

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Big thanks go to Mathias Kolehmainen for reporting the bug, providing
debug output and testing the patches I sent him to get it working.

The fix was to stop calling ntfs_attr_set() at mount time as that causes
balance_dirty_pages_ratelimited() to be called which on systems with
little memory actually tries to go and balance the dirty pages which tries
to take the s_umount semaphore but because we are still in fill_super()
across which the VFS holds s_umount for writing this results in a
deadlock.

We now do the dirty work by hand by submitting individual buffers.  This
has the annoying "feature" that mounting can take a few seconds if the
journal is large as we have clear it all.  One day someone should improve
on this by deferring the journal clearing to a helper kernel thread so it
can be done in the background but I don't have time for this at the moment
and the current solution works fine so I am leaving it like this for now.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Anton Altaparmakov
2007-10-12 09:37:15 +01:00
committed by Linus Torvalds
parent f26e51f67a
commit bfab36e816
9 changed files with 181 additions and 53 deletions
Download Patch File Download Diff File Expand all files Collapse all files

143
fs/ntfs/logfile.c
View File

@@ -1,7 +1,7 @@
/*
* logfile.c - NTFS kernel journal handling. Part of the Linux-NTFS project.
*
* Copyright (c) 2002-2005 Anton Altaparmakov
* Copyright (c) 2002-2007 Anton Altaparmakov
*
* This program/include file is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as published
@@ -724,24 +724,139 @@ bool ntfs_is_logfile_clean(struct inode *log_vi, const RESTART_PAGE_HEADER *rp)
*/
bool ntfs_empty_logfile(struct inode *log_vi)
{
ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
VCN vcn, end_vcn;
ntfs_inode *log_ni = NTFS_I(log_vi);
ntfs_volume *vol = log_ni->vol;
struct super_block *sb = vol->sb;
runlist_element *rl;
unsigned long flags;
unsigned block_size, block_size_bits;
int err;
bool should_wait = true;
ntfs_debug("Entering.");
if (!NVolLogFileEmpty(vol)) {
int err;
err = ntfs_attr_set(NTFS_I(log_vi), 0, i_size_read(log_vi),
0xff);
if (unlikely(err)) {
ntfs_error(vol->sb, "Failed to fill $LogFile with "
"0xff bytes (error code %i).", err);
return false;
}
/* Set the flag so we do not have to do it again on remount. */
NVolSetLogFileEmpty(vol);
if (NVolLogFileEmpty(vol)) {
ntfs_debug("Done.");
return true;
}
/*
* We cannot use ntfs_attr_set() because we may be still in the middle
* of a mount operation. Thus we do the emptying by hand by first
* zapping the page cache pages for the $LogFile/$DATA attribute and
* then emptying each of the buffers in each of the clusters specified
* by the runlist by hand.
*/
block_size = sb->s_blocksize;
block_size_bits = sb->s_blocksize_bits;
vcn = 0;
read_lock_irqsave(&log_ni->size_lock, flags);
end_vcn = (log_ni->initialized_size + vol->cluster_size_mask) >>
vol->cluster_size_bits;
read_unlock_irqrestore(&log_ni->size_lock, flags);
truncate_inode_pages(log_vi->i_mapping, 0);
down_write(&log_ni->runlist.lock);
rl = log_ni->runlist.rl;
if (unlikely(!rl || vcn < rl->vcn || !rl->length)) {
map_vcn:
err = ntfs_map_runlist_nolock(log_ni, vcn, NULL);
if (err) {
ntfs_error(sb, "Failed to map runlist fragment (error "
"%d).", -err);
goto err;
}
rl = log_ni->runlist.rl;
BUG_ON(!rl || vcn < rl->vcn || !rl->length);
}
/* Seek to the runlist element containing @vcn. */
while (rl->length && vcn >= rl[1].vcn)
rl++;
do {
LCN lcn;
sector_t block, end_block;
s64 len;
/*
* If this run is not mapped map it now and start again as the
* runlist will have been updated.
*/
lcn = rl->lcn;
if (unlikely(lcn == LCN_RL_NOT_MAPPED)) {
vcn = rl->vcn;
goto map_vcn;
}
/* If this run is not valid abort with an error. */
if (unlikely(!rl->length || lcn < LCN_HOLE))
goto rl_err;
/* Skip holes. */
if (lcn == LCN_HOLE)
continue;
block = lcn << vol->cluster_size_bits >> block_size_bits;
len = rl->length;
if (rl[1].vcn > end_vcn)
len = end_vcn - rl->vcn;
end_block = (lcn + len) << vol->cluster_size_bits >>
block_size_bits;
/* Iterate over the blocks in the run and empty them. */
do {
struct buffer_head *bh;
/* Obtain the buffer, possibly not uptodate. */
bh = sb_getblk(sb, block);
BUG_ON(!bh);
/* Setup buffer i/o submission. */
lock_buffer(bh);
bh->b_end_io = end_buffer_write_sync;
get_bh(bh);
/* Set the entire contents of the buffer to 0xff. */
memset(bh->b_data, -1, block_size);
if (!buffer_uptodate(bh))
set_buffer_uptodate(bh);
if (buffer_dirty(bh))
clear_buffer_dirty(bh);
/*
* Submit the buffer and wait for i/o to complete but
* only for the first buffer so we do not miss really
* serious i/o errors. Once the first buffer has
* completed ignore errors afterwards as we can assume
* that if one buffer worked all of them will work.
*/
submit_bh(WRITE, bh);
if (should_wait) {
should_wait = false;
wait_on_buffer(bh);
if (unlikely(!buffer_uptodate(bh)))
goto io_err;
}
brelse(bh);
} while (++block < end_block);
} while ((++rl)->vcn < end_vcn);
up_write(&log_ni->runlist.lock);
/*
* Zap the pages again just in case any got instantiated whilst we were
* emptying the blocks by hand. FIXME: We may not have completed
* writing to all the buffer heads yet so this may happen too early.
* We really should use a kernel thread to do the emptying
* asynchronously and then we can also set the volume dirty and output
* an error message if emptying should fail.
*/
truncate_inode_pages(log_vi->i_mapping, 0);
/* Set the flag so we do not have to do it again on remount. */
NVolSetLogFileEmpty(vol);
ntfs_debug("Done.");
return true;
io_err:
ntfs_error(sb, "Failed to write buffer. Unmount and run chkdsk.");
goto dirty_err;
rl_err:
ntfs_error(sb, "Runlist is corrupt. Unmount and run chkdsk.");
dirty_err:
NVolSetErrors(vol);
err = -EIO;
err:
up_write(&log_ni->runlist.lock);
ntfs_error(sb, "Failed to fill $LogFile with 0xff bytes (error %d).",
-err);
return false;
}
#endif /* NTFS_RW */