Commit Graph

1349 Commits

Author SHA1 Message Date
Aditya Kali
5356f2615c ext4: attempt to fix race in bigalloc code path
Currently, there exists a race between delayed allocated writes and
the writeback when bigalloc feature is in use. The race was because we
wanted to determine what blocks in a cluster are under delayed
allocation and we were using buffer_delayed(bh) check for it. But, the
writeback codepath clears this bit without any synchronization which
resulted in a race and an ext4 warning similar to:

EXT4-fs (ram1): ext4_da_update_reserve_space: ino 13, used 1 with only 0
		reserved data blocks

The race existed in two places.
(1) between ext4_find_delalloc_range() and ext4_map_blocks() when called from
    writeback code path.
(2) between ext4_find_delalloc_range() and ext4_da_get_block_prep() (where
    buffer_delayed(bh) is set.

To fix (1), this patch introduces a new buffer_head state bit -
BH_Da_Mapped.  This bit is set under the protection of
EXT4_I(inode)->i_data_sem when we have actually mapped the delayed
allocated blocks during the writeout time. We can now reliably check
for this bit inside ext4_find_delalloc_range() to determine whether
the reservation for the blocks have already been claimed or not.

To fix (2), it was necessary to set buffer_delay(bh) under the
protection of i_data_sem.  So, I extracted the very beginning of
ext4_map_blocks into a new function - ext4_da_map_blocks() - and
performed the required setting of bh_delay bit and the quota
reservation under the protection of i_data_sem.  These two fixes makes
the checking of buffer_delay(bh) and buffer_da_mapped(bh) consistent,
thus removing the race.

Tested: I was able to reproduce the problem by running 'dd' and
'fsync' in parallel. Also, xfstests sometimes used to reproduce this
race. After the fix both my test and xfstests were successful and no
race (warning message) was observed.

Google-Bug-Id: 4997027

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:20:51 -04:00
Aditya Kali
d8990240d8 ext4: add some tracepoints in ext4/extents.c
This patch adds some tracepoints in ext4/extents.c and updates a tracepoint in
ext4/inode.c.

Tested: Built and ran the kernel and verified that these tracepoints work.
Also ran xfstests.

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:18:51 -04:00
Theodore Ts'o
df55c99dc8 ext4: rename ext4_has_free_blocks() to ext4_has_free_clusters()
Rename the function so it is more clear what is going on.  Also rename
the various variables so it's clearer what's happening.

Also fix a missing blocks to cluster conversion when reading the
number of reserved blocks for root.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:16:51 -04:00
Theodore Ts'o
e7d5f3156e ext4: rename ext4_claim_free_blocks() to ext4_claim_free_clusters()
This function really claims a number of free clusters, not blocks, so
rename it so it's clearer what's going on.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:14:51 -04:00
Theodore Ts'o
cff1dfd767 ext4: rename ext4_free_blocks_after_init() to ext4_free_clusters_after_init()
This function really returns the number of clusters after initializing
an uninitalized block bitmap has been initialized.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:12:51 -04:00
Theodore Ts'o
5dee54372c ext4: rename ext4_count_free_blocks() to ext4_count_free_clusters()
This function really counts the free clusters reported in the block
group descriptors, so rename it to reduce confusion.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:10:51 -04:00
Theodore Ts'o
021b65bb1e ext4: Rename ext4_free_blks_{count,set}() to refer to clusters
The field bg_free_blocks_count_{lo,high} in the block group
descriptor has been repurposed to hold the number of free clusters for
bigalloc functions.  So rename the functions so it makes it easier to
read and audit the block allocation and block freeing code.

Note: at this point in bigalloc development we doesn't support
online resize, so this also makes it really obvious all of the places
we need to fix up to add support for online resize.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:08:51 -04:00
Theodore Ts'o
6f16b60690 ext4: enable mounting bigalloc as read/write
Now that we have implemented all of the changes needed for bigalloc,
we can finally enable it!

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:06:51 -04:00
Aditya Kali
7b415bf60f ext4: Fix bigalloc quota accounting and i_blocks value
With bigalloc changes, the i_blocks value was not correctly set (it was still
set to number of blocks being used, but in case of bigalloc, we want i_blocks
to represent the number of clusters being used). Since the quota subsystem sets
the i_blocks value, this patch fixes the quota accounting and makes sure that
the i_blocks value is set correctly.

Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:04:51 -04:00
Theodore Ts'o
27baebb849 ext4: tune mballoc's default group prealloc size for bigalloc file systems
The default group preallocation size had been previously set to 512
blocks/clusters, regardless of the block/cluster size.  This is
probably too big for large cluster sizes.  So adjust the default so
that it is 2 megabytes or 32 clusters, whichever is larger.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:02:51 -04:00
Theodore Ts'o
f975d6bcc7 ext4: teach ext4_statfs() to deal with clusters if bigalloc is enabled
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 19:00:51 -04:00
Theodore Ts'o
24aaa8ef4e ext4: convert the free_blocks field in s_flex_groups to be free_clusters
Convert the free_blocks to be free_clusters to make the final revised
bigalloc changes easier to read/understand.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:58:51 -04:00
Theodore Ts'o
5704265188 ext4: convert s_{dirty,free}blocks_counter to s_{dirty,free}clusters_counter
Convert the percpu counters s_dirtyblocks_counter and
s_freeblocks_counter in struct ext4_super_info to be
s_dirtyclusters_counter and s_freeclusters_counter.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:56:51 -04:00
Theodore Ts'o
0aa060000e ext4: teach ext4_ext_truncate() about the bigalloc feature
When we are truncating (as opposed unlinking) a file, we need to worry
about partial truncates of a file, especially in the light of sparse
files.  The changes here make sure that arbitrary truncates of sparse
files works correctly.  Yeah, it's messy.

Note that these functions will need to be revisted when the punch
ioctl is integrated --- in fact this commit will probably have merge
conflicts with the punch changes which Allison Henders and the IBM LTC
have been working on.  I will need to fix this up when either patch
hits mainline.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:54:51 -04:00
Theodore Ts'o
4d33b1ef10 ext4: teach ext4_ext_map_blocks() about the bigalloc feature
If we need to allocate a new block in ext4_ext_map_blocks(), the
function needs to see if the cluster has already been allocated.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:52:51 -04:00
Theodore Ts'o
84130193e0 ext4: teach ext4_free_blocks() about bigalloc and clusters
The ext4_free_blocks() function now has two new flags that indicate
whether a partial cluster at the beginning or the end of the block
extents should be freed or not.  That will be up the caller (i.e.,
truncate), who can figure out whether partial clusters at the
beginning or the end of a block range can be freed.

We also have to update the ext4_mb_free_metadata() and
release_blocks_on_commit() machinery to be cluster-based, since it is
used by ext4_free_blocks().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:50:51 -04:00
Theodore Ts'o
53accfa9f8 ext4: teach mballoc preallocation code about bigalloc clusters
In most of mballoc.c, we do everything in units of clusters, since the
block allocation bitmaps and buddy bitmaps are all denominated in
clusters.  The one place where we do deal with absolute block numbers
is in the code that handles the preallocation regions, since in the
case of inode-based preallocation regions, the start of the
preallocation region can't be relative to the beginning of the group.

So this adds a bit of complexity, where pa_pstart and pa_lstart are
block numbers, while pa_free, pa_len, and fe_len are denominated in
units of clusters.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:48:51 -04:00
Theodore Ts'o
3212a80a58 ext4: convert block group-relative offsets to use clusters
Certain parts of the ext4 code base, primarily in mballoc.c, use a
block group number and offset from the beginning of the block group.
This offset is invariably used to index into the allocation bitmap, so
change the offset to be denominated in units of clusters.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:46:51 -04:00
Theodore Ts'o
d5b8f31007 ext4: bigalloc changes to block bitmap initialization functions
Add bigalloc support to ext4_init_block_bitmap() and
ext4_free_blocks_after_init().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:44:51 -04:00
Theodore Ts'o
fd034a84e1 ext4: split out ext4_free_blocks_after_init()
The function ext4_free_blocks_after_init() used to be a #define of
ext4_init_block_bitmap().  This actually made it difficult to
understand how the function worked, and made it hard make changes to
support clusters.  So as an initial cleanup, I've separated out the
functionality of initializing block bitmap from calculating the number
of free blocks in the new block group.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:42:51 -04:00
Theodore Ts'o
49f7f9af4b ext4: factor out block group accounting into functions
This makes it easier to understand how ext4_init_block_bitmap() works,
and it will assist when we split out ext4_free_blocks_after_init() in
the next commit.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:40:51 -04:00
Theodore Ts'o
7137d7a48e ext4: convert instances of EXT4_BLOCKS_PER_GROUP to EXT4_CLUSTERS_PER_GROUP
Change the places in fs/ext4/mballoc.c where EXT4_BLOCKS_PER_GROUP are
used to indicate the number of bits in a block bitmap (which is really
a cluster allocation bitmap in bigalloc file systems).  There are
still some places in the ext4 codebase where usage of
EXT4_BLOCKS_PER_GROUP needs to be audited/fixed, in code paths that
aren't used given the initial restricted assumptions for bigalloc.
These will need to be fixed before we can relax those restrictions.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:38:51 -04:00
Theodore Ts'o
bab08ab964 ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.)
At least initially if the bigalloc feature is enabled, we will not
support non-extent mapped inodes, online resizing, online defrag, or
the FITRIM ioctl.  This simplifies the initial implementation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:36:51 -04:00
Theodore Ts'o
281b599597 ext4: read-only support for bigalloc file systems
This adds supports for bigalloc file systems.  It teaches the mount
code just enough about bigalloc superblock fields that it will mount
the file system without freaking out that the number of blocks per
group is too big.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:34:51 -04:00
Theodore Ts'o
7c2e70879f ext4: add ext4-specific kludge to avoid an oops after the disk disappears
The del_gendisk() function uninitializes the disk-specific data
structures, including the bdi structure, without telling anyone
else.  Once this happens, any attempt to call mark_buffer_dirty()
(for example, by ext4_commit_super), will cause a kernel OOPS.

Fix this for now until we can fix things in an architecturally correct
way.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:28:51 -04:00
Allison Henderson
02fac1297e ext4: fix partial page writes
While running extended fsx tests to verify the preceeding patches,
a similar bug was also found in the write operation

When ever a write operation begins or ends in a hole,
or extends EOF, the partial page contained in the hole
or beyond EOF needs to be zeroed out.

To correct this the new ext4_discard_partial_page_buffers_no_lock
routine is used to zero out the partial page, but only for buffer
heads that are already unmapped.

Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-06 21:53:01 -04:00
Allison Henderson
189e868fa8 ext4: fix fsx truncate failure
While running extended fsx tests to verify the first
two patches, a similar bug was also found in the
truncate operation.

This bug happens because the truncate routine only zeros
the unblock aligned portion of the last page.  This means
that the block aligned portions of the page appearing after
i_size are left unzeroed, and the buffer heads still mapped.

This bug is corrected by using ext4_discard_partial_page_buffers
in the truncate routine to zero the partial page and unmap
the buffer headers.

Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-06 21:49:44 -04:00
Theodore Ts'o
decbd919f4 ext4: only call ext4_jbd2_file_inode when an inode has been extended
In delayed allocation mode, it's important to only call
ext4_jbd2_file_inode when the file has been extended.  This is
necessary to avoid a race which first got introduced in commit
678aaf481, but which was made much more common with the introduction
of the "punch hole" functionality.  (Especially when dioread_nolock
was enabled; when I could reliably reproduce this problem with
xfstests #74.)

The race is this: If while trying to writeback a delayed allocation
inode, there is a need to map delalloc blocks, and we run out of space
in the journal, *and* at the same time the inode is already on the
committing transaction's t_inode_list (because for example while doing
the punch hole operation, ext4_jbd2_file_inode() is called), then the
commit operation will wait for the inode to finish all of its pending
writebacks by calling filemap_fdatawait(), but since that inode has
one or more pages with the PageWriteback flag set, the commit
operation will wait forever, and the so the writeback of the inode can
never take place, and the kjournald thread and the writeback thread
end up waiting for each other --- forever.

It's important at this point to recall why an inode is placed on the
t_inode_list; it is to provide the data=ordered guarantees that we
don't end up exposing stale data.  In the case where we are truncating
or punching a hole in the inode, there is no possibility that stale
data could be exposed in the first place, so we don't need to put the
inode on the t_inode_list!

The right long-term fix is to get rid of data=ordered mode altogether,
and only update the extent tree or indirect blocks after the data has
been written.  Until then, this change will also avoid some
unnecessary waiting in the commit operation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Allison Henderson <achender@linux.vnet.ibm.com>
Cc: Jan Kara <jack@suse.cz>
2011-09-06 02:37:06 -04:00
Theodore Ts'o
9ea7a0df63 jbd2: add debugging information to jbd2_journal_dirty_metadata()
Add debugging information in case jbd2_journal_dirty_metadata() is
called with a buffer_head which didn't have
jbd2_journal_get_write_access() called on it, or if the journal_head
has the wrong transaction in it.  In addition, return an error code.
This won't change anything for ocfs2, which will BUG_ON() the non-zero
exit code.

For ext4, the caller of this function is ext4_handle_dirty_metadata(),
and on seeing a non-zero return code, will call __ext4_journal_stop(),
which will print the function and line number of the (buggy) calling
function and abort the journal.  This will allow us to recover instead
of bug halting, which is better from a robustness and reliability
point of view.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-04 10:18:14 -04:00
Theodore Ts'o
56889787cf ext4: improve handling of conflicting mount options
If the user explicitly specifies conflicting mount options for
delalloc or dioread_nolock and data=journal, fail the mount, instead
of printing a warning and continuing (since many user's won't look at
dmesg and notice the warning).

Also, print a single warning that data=journal implies that delayed
allocation is not on by default (since it's not supported), and
furthermore that O_DIRECT is not supported.  Improve the text in
Documentation/filesystems/ext4.txt so this is clear there as well.

Similarly, if the dioread_nolock mount option is specified when the
file system block size != PAGE_SIZE, fail the mount instead of
printing a warning message and ignoring the mount option.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-03 18:22:38 -04:00
Allison Henderson
2be4751b21 ext4: fix 2nd xfstests 127 punch hole failure
This patch fixes a second punch hole bug found by xfstests 127.

This bug happens because punch hole needs to flush the pages
of the hole to avoid race conditions.  But if the end of the
hole is in the same page as i_size, the buffer heads beyond
i_size need to be unmapped and the page needs to be zeroed
after it is flushed.

To correct this, the new ext4_discard_partial_page_buffers
routine is used to zero and unmap the partial page
beyond i_size if the end of the hole appears in the same
page as i_size.

The code has also been optimized to set the end of the hole
to the page after i_size if the specified hole exceeds i_size,
and the code that flushes the pages has been simplified.

Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
2011-09-03 11:56:52 -04:00
Allison Henderson
ba06208a13 ext4: fix xfstests 75, 112, 127 punch hole failure
This patch addresses a bug found by xfstests 75, 112, 127
when blocksize = 1k

This bug happens because the punch hole code only zeros
out non block aligned regions of the page.  This means that if the
blocks are smaller than a page, then the block aligned regions of
the page inside the hole are left un-zeroed, and their buffer heads
are still mapped.  This bug is corrected by using
ext4_discard_partial_page_buffers to properly zero the partial page
at the head and tail of the hole, and unmap the corresponding buffer
heads

This patch also addresses a bug reported by Lukas while working on a
new patch to add discard support for loop devices using punch hole.
The bug happened because of the first and last block number
needed to be cast to a larger data type before calculating the
byte offset, but since now we only need the byte offsets of the
pages, we no longer even need to be calculating the byte offsets
of the blocks.  The code to do the block offset calculations is
removed in this patch.

Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
2011-09-03 11:55:59 -04:00
Allison Henderson
4e96b2dbbf ext4: Add new ext4_discard_partial_page_buffers routines
This patch adds two new routines: ext4_discard_partial_page_buffers
and ext4_discard_partial_page_buffers_no_lock.

The ext4_discard_partial_page_buffers routine is a wrapper
function to ext4_discard_partial_page_buffers_no_lock.
The wrapper function locks the page and passes it to
ext4_discard_partial_page_buffers_no_lock.
Calling functions that already have the page locked can call
ext4_discard_partial_page_buffers_no_lock directly.

The ext4_discard_partial_page_buffers_no_lock function
zeros a specified range in a page, and unmaps the
corresponding buffer heads.  Only block aligned regions of the
page will have their buffer heads unmapped.  Unblock aligned regions
will be mapped if needed so that they can be updated with the
partial zero out.  This function is meant to
be used to update a page and its buffer heads to be zeroed
and unmapped when the corresponding blocks have been released
or will be released.

This routine is used in the following scenarios:
* A hole is punched and the non page aligned regions
  of the head and tail of the hole need to be discarded

* The file is truncated and the partial page beyond EOF needs
  to be discarded

* The end of a hole is in the same page as EOF.  After the
  page is flushed, the partial page beyond EOF needs to be
  discarded.

* A write operation begins or ends inside a hole and the partial
  page appearing before or after the write needs to be discarded

* A write operation extends EOF and the partial page beyond EOF
  needs to be discarded

This function takes a flag EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED
which is used when a write operation begins or ends in a hole.
When the EXT4_DISCARD_PARTIAL_PG_ZERO_UNMAPPED flag is used, only
buffer heads that are already unmapped will have the corresponding
regions of the page zeroed.

Signed-off-by: Allison Henderson <achender@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-03 11:51:09 -04:00
Theodore Ts'o
5930ea6438 ext4: call ext4_handle_dirty_metadata with correct inode in ext4_dx_add_entry
ext4_dx_add_entry manipulates bh2 and frames[0].bh, which are two buffer_heads
that point to directory blocks assigned to the directory inode.  However, the
function calls ext4_handle_dirty_metadata with the inode of the file that's
being added to the directory, not the directory inode itself.  Therefore,
correct the code to dirty the directory buffers with the directory inode, not
the file inode.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-31 12:02:51 -04:00
Darrick J. Wong
f9287c1f2d ext4: ext4_mkdir should dirty dir_block with newly created directory inode
ext4_mkdir calls ext4_handle_dirty_metadata with dir_block and the inode "dir".
Unfortunately, dir_block belongs to the newly created directory (which is
"inode"), not the parent directory (which is "dir").  Fix the incorrect
association.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-31 12:00:51 -04:00
Darrick J. Wong
bcaa992975 ext4: ext4_rename should dirty dir_bh with the correct directory
When ext4_rename performs a directory rename (move), dir_bh is a
buffer that is modified to update the '..' link in the directory being
moved (old_inode).  However, ext4_handle_dirty_metadata is called with
the old parent directory inode (old_dir) and dir_bh, which is
incorrect because dir_bh does not belong to the parent inode.  Fix
this error.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-31 11:58:51 -04:00
Theodore Ts'o
84ebd79561 ext4: fake direct I/O mode for data=journal
Currently attempts to open a file with O_DIRECT in data=journal mode
causes the open to fail with -EINVAL.  This makes it very hard to test
data=journal mode.  So we will let the open succeed, but then always
fall back to O_DSYNC buffered writes.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-08-31 11:56:51 -04:00
Theodore Ts'o
1cd9f0976a ext2,ext3,ext4: don't inherit APPEND_FL or IMMUTABLE_FL for new inodes
This doesn't make much sense, and it exposes a bug in the kernel where
attempts to create a new file in an append-only directory using
O_CREAT will fail (but still leave a zero-length file).  This was
discovered when xfstests #79 was generalized so it could run on all
file systems.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc:stable@kernel.org
2011-08-31 11:54:51 -04:00
Jiaying Zhang
8c0bec2151 ext4: remove i_mutex lock in ext4_evict_inode to fix lockdep complaining
The i_mutex lock and flush_completed_IO() added by commit 2581fdc810
in ext4_evict_inode() causes lockdep complaining about potential
deadlock in several places.  In most/all of these LOCKDEP complaints
it looks like it's a false positive, since many of the potential
circular locking cases can't take place by the time the
ext4_evict_inode() is called; but since at the very least it may mask
real problems, we need to address this.

This change removes the flush_completed_IO() and i_mutex lock in
ext4_evict_inode().  Instead, we take a different approach to resolve
the software lockup that commit 2581fdc810 intends to fix.  Rather
than having ext4-dio-unwritten thread wait for grabing the i_mutex
lock of an inode, we use mutex_trylock() instead, and simply requeue
the work item if we fail to grab the inode's i_mutex lock.

This should speed up work queue processing in general and also
prevents the following deadlock scenario: During page fault,
shrink_icache_memory is called that in turn evicts another inode B.
Inode B has some pending io_end work so it calls ext4_ioend_wait()
that waits for inode B's i_ioend_count to become zero.  However, inode
B's ioend work was queued behind some of inode A's ioend work on the
same cpu's ext4-dio-unwritten workqueue.  As the ext4-dio-unwritten
thread on that cpu is processing inode A's ioend work, it tries to
grab inode A's i_mutex lock.  Since the i_mutex lock of inode A is
still hold before the page fault happened, we enter a deadlock.

Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-08-31 11:50:51 -04:00
Linus Torvalds
c063d8a60f Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: flush any pending end_io requests before DIO reads w/dioread_nolock
  ext4: fix nomblk_io_submit option so it correctly converts uninit blocks
  ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
  ext4: call ext4_ioend_wait and ext4_flush_completed_IO in ext4_evict_inode
  ext4: Fix ext4_should_writeback_data() for no-journal mode
2011-08-21 06:59:41 -07:00
Jiaying Zhang
dccaf33fa3 ext4: flush any pending end_io requests before DIO reads w/dioread_nolock
There is a race between ext4 buffer write and direct_IO read with
dioread_nolock mount option enabled. The problem is that we clear
PageWriteback flag during end_io time but will do
uninitialized-to-initialized extent conversion later with dioread_nolock.
If an O_direct read request comes in during this period, ext4 will return
zero instead of the recently written data.

This patch checks whether there are any pending uninitialized-to-initialized
extent conversion requests before doing O_direct read to close the race.
Note that this is just a bandaid fix. The fundamental issue is that we
clear PageWriteback flag before we really complete an IO, which is
problem-prone. To fix the fundamental issue, we may need to implement an
extent tree cache that we can use to look up pending to-be-converted extents.

Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-19 19:13:32 -04:00
Theodore Ts'o
9dd75f1f1a ext4: fix nomblk_io_submit option so it correctly converts uninit blocks
Bug discovered by Jan Kara:

Finally, commit 1449032be1 returned back
the old IO submission code but apparently it forgot to return the old
handling of uninitialized buffers so we unconditionnaly call
block_write_full_page() without specifying end_io function. So AFAICS
we never convert unwritten extents to written in some cases. For
example when I mount the fs as: mount -t ext4 -o
nomblk_io_submit,dioread_nolock /dev/ubdb /mnt and do
        int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0600);
        char buf[1024];
        memset(buf, 'a', sizeof(buf));
        fallocate(fd, 0, 0, 16384);
        write(fd, buf, sizeof(buf));

I get a file full of zeros (after remounting the filesystem so that
pagecache is dropped) instead of seeing the first KB contain 'a's.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-13 12:58:21 -04:00
Tao Ma
32c80b32c0 ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear
the flag and decrease the counter in the same time.

We don't increase i_aiodio_unwritten when setting
EXT4_IO_END_UNWRITTEN so it will go nagative and causes some process
to wait forever.

Part of the patch came from Eric in his e-mail, but it doesn't fix the
problem met by Michael actually.

http://marc.info/?l=linux-ext4&m=131316851417460&w=2

Reported-and-Tested-by: Michael Tokarev<mjt@tls.msk.ru>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-13 12:30:59 -04:00
Jiaying Zhang
2581fdc810 ext4: call ext4_ioend_wait and ext4_flush_completed_IO in ext4_evict_inode
Flush inode's i_completed_io_list before calling ext4_io_wait to
prevent the following deadlock scenario: A page fault happens while
some process is writing inode A. During page fault,
shrink_icache_memory is called that in turn evicts another inode
B. Inode B has some pending io_end work so it calls ext4_ioend_wait()
that waits for inode B's i_ioend_count to become zero. However, inode
B's ioend work was queued behind some of inode A's ioend work on the
same cpu's ext4-dio-unwritten workqueue. As the ext4-dio-unwritten
thread on that cpu is processing inode A's ioend work, it tries to
grab inode A's i_mutex lock. Since the i_mutex lock of inode A is
still hold before the page fault happened, we enter a deadlock.

Also moves ext4_flush_completed_IO and ext4_ioend_wait from
ext4_destroy_inode() to ext4_evict_inode(). During inode deleteion,
ext4_evict_inode() is called before ext4_destroy_inode() and in
ext4_evict_inode(), we may call ext4_truncate() without holding
i_mutex lock. As a result, there is a race between flush_completed_IO
that is called from ext4_ext_truncate() and ext4_end_io_work, which
may cause corruption on an io_end structure. This change moves
ext4_flush_completed_IO and ext4_ioend_wait from ext4_destroy_inode()
to ext4_evict_inode() to resolve the race between ext4_truncate() and
ext4_end_io_work during inode deletion.

Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-13 12:17:13 -04:00
Curt Wohlgemuth
441c850857 ext4: Fix ext4_should_writeback_data() for no-journal mode
ext4_should_writeback_data() had an incorrect sequence of
tests to determine if it should return 0 or 1: in
particular, even in no-journal mode, 0 was being returned
for a non-regular-file inode.

This meant that, in non-journal mode, we would use
ext4_journalled_aops for directories, symlinks, and other
non-regular files.  However, calling journalled aop
callbacks when there is no valid handle, can cause problems.

This would cause a kernel crash with Jan Kara's commit
2d859db3e4 ("ext4: fix data corruption in inodes with
journalled data"), because we now dereference 'handle' in
ext4_journalled_write_end().

I also added BUG_ONs to check for a valid handle in the
obviously journal-only aops callbacks.

I tested this running xfstests with a scratch device in
these modes:

   - no-journal
   - data=ordered
   - data=writeback
   - data=journal

All work fine; the data=journal run has many failures and a
crash in xfstests 074, but this is no different from a
vanilla kernel.

Signed-off-by: Curt Wohlgemuth <curtw@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
2011-08-13 11:25:18 -04:00
Eric Sandeen
8c20871998 ext4: Properly count journal credits for long symlinks
Commit df5e622340 ("ext4: fix deadlock in ext4_symlink() in ENOSPC
conditions") recalculated the number of credits needed for a long
symlink, in the process of splitting it into two transactions.  However,
the first credit calculation under-counted because if selinux is
enabled, credits are needed to create the selinux xattr as well.

Overrunning the reservation will result in an OOPS in
jbd2_journal_dirty_metadata() due to this assert:

  J_ASSERT_JH(jh, handle->h_buffer_credits > 0);

Fix this by increasing the reservation size.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-11 17:23:40 -07:00
Mathias Krause
db9481c047 ext4: use kzalloc in ext4_kzalloc()
Commit 9933fc0i (ext4: introduce ext4_kvmalloc(), ext4_kzalloc(), and
ext4_kvfree()) intruduced wrappers around k*alloc/vmalloc but introduced
a typo for ext4_kzalloc() by not using kzalloc() but kmalloc().

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-08-03 14:57:11 -04:00
Linus Torvalds
60ad446682 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (60 commits)
  ext4: prevent memory leaks from ext4_mb_init_backend() on error path
  ext4: use EXT4_BAD_INO for buddy cache to avoid colliding with valid inode #
  ext4: use ext4_msg() instead of printk in mballoc
  ext4: use ext4_kvzalloc()/ext4_kvmalloc() for s_group_desc and s_group_info
  ext4: introduce ext4_kvmalloc(), ext4_kzalloc(), and ext4_kvfree()
  ext4: use the correct error exit path in ext4_init_inode_table()
  ext4: add missing kfree() on error return path in add_new_gdb()
  ext4: change umode_t in tracepoint headers to be an explicit __u16
  ext4: fix races in ext4_sync_parent()
  ext4: Fix overflow caused by missing cast in ext4_fallocate()
  ext4: add action of moving index in ext4_ext_rm_idx for Punch Hole
  ext4: simplify parameters of reserve_backup_gdb()
  ext4: simplify parameters of add_new_gdb()
  ext4: remove lock_buffer in bclean() and setup_new_group_blocks()
  ext4: simplify journal handling in setup_new_group_blocks()
  ext4: let setup_new_group_blocks() set multiple bits at a time
  ext4: fix a typo in ext4_group_extend()
  ext4: let ext4_group_add_blocks() handle 0 blocks quickly
  ext4: let ext4_group_add_blocks() return an error code
  ext4: rename ext4_add_groupblocks() to ext4_group_add_blocks()
  ...

Fix up conflict in fs/ext4/inode.c: commit aacfc19c62 ("fs: simplify
the blockdev_direct_IO prototype") had changed the ext4_ind_direct_IO()
function for the new simplified calling convention, while commit
dae1e52cb1 ("ext4: move ext4_ind_* functions from inode.c to
indirect.c") moved the function to another file.
2011-08-01 13:56:03 -10:00
Yu Jian
79a77c5ac3 ext4: prevent memory leaks from ext4_mb_init_backend() on error path
In ext4_mb_init(), if the s_locality_group allocation fails it will
currently cause the allocations made in ext4_mb_init_backend() to
be leaked.  Moving the ext4_mb_init_backend() allocation after the
s_locality_group allocation avoids that problem.

Signed-off-by: Yu Jian <yujian@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-08-01 17:41:46 -04:00
Yu Jian
48e6061bf4 ext4: use EXT4_BAD_INO for buddy cache to avoid colliding with valid inode #
Signed-off-by: Yu Jian <yujian@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-08-01 17:41:39 -04:00