kernel.git/fs/gfs2/log.c, branch linux-3.14.y

GFS2: Fix use-after-free race when calling gfs2_remove_from_ail

2013-12-13T21:42:23Z

Function gfs2_remove_from_ail drops the reference on the bh via brelse. This patch fixes a race condition whereby bh is deferenced after the brelse when setting bd->bd_blkno = bh->b_blocknr; Under certain rare circumstances, bh might be gone or reused, and bd->bd_blkno is set to whatever that memory happens to be, which is often 0. Later, in gfs2_trans_add_unrevoke, that bd fails the test "bd->bd_blkno >= blkno" which causes it to never be freed. The end result is that the bd is never freed from the bufdata cache, which results in this error: slab error in kmem_cache_destroy(): cache `gfs2_bufdata': Can't free all objects Signed-off-by: Bob Peterson Signed-off-by: Steven Whitehouse

GFS2: aggressively issue revokes in gfs2_log_flush

2013-06-19T08:41:59Z

This patch looks at all the outstanding blocks in all the transactions on the log, and moves the completed ones to the ail2 list. Then it issues revokes for these blocks. This will hopefully speed things up in situations where there is a lot of contention for glocks, especially if they are acquired serially. revoke_lo_before_commit will issue at most one log block's full of these preemptive revokes. The amount of reserved log space that gfs2_log_reserve() ignores has been incremented to allow for this extra block. This patch also consolidates the common revoke instructions into one function, gfs2_add_revoke(). Signed-off-by: Benjamin Marzinski Signed-off-by: Steven Whitehouse

GFS2: replace gfs2_ail structure with gfs2_trans

2013-04-08T07:46:22Z

In order to allow transactions and log flushes to happen at the same time, gfs2 needs to move the transaction accounting and active items list code into the gfs2_trans structure. As a first step toward this, this patch removes the gfs2_ail structure, and handles the active items list in the gfs_trans structure. This keeps gfs2 from allocating an ail structure on log flushes, and gives us a struture that can later be used to store the transaction accounting outside of the gfs2 superblock structure. With this patch, at the end of a transaction, gfs2 will add the gfs2_trans structure to the superblock if there is not one already. This structure now has the active items fields that were previously in gfs2_ail. This is not necessary in the case where the transaction was simply used to add revokes, since these are never written outside of the journal, and thus, don't need an active items list. Also, in order to make sure that the transaction structure is not removed while it's still in use by gfs2_trans_end, unlocking the sd_log_flush_lock has to happen slightly later in ending the transaction. Signed-off-by: Benjamin Marzinski Signed-off-by: Steven Whitehouse

GFS2: Use ->writepages for ordered writes

2013-01-29T10:29:17Z

Instead of using a list of buffers to write ahead of the journal flush, this now uses a list of inodes and calls ->writepages via filemap_fdatawrite() in order to achieve the same thing. For most use cases this results in a shorter ordered write list, as well as much larger i/os being issued. The ordered write list is sorted by inode number before writing in order to retain the disk block ordering between inodes as per the previous code. The previous ordered write code used to conflict in its assumptions about how to write out the disk blocks with mpage_writepages() so that with this updated version we can also use mpage_writepages() for GFS2's ordered write, writepages implementation. So we will also send larger i/os from writeback too. Signed-off-by: Steven Whitehouse

GFS2: eliminate log elements and simplify

2012-05-02T08:14:36Z

This patch eliminates the gfs2_log_element data structure and rolls its two components into the gfs2_bufdata. This makes the code easier to understand and makes it easier to migrate to a rbtree to keep the list sorted. Signed-off-by: Bob Peterson Signed-off-by: Steven Whitehouse

GFS2: Log code fixes

2012-04-24T15:44:38Z

This patch removes a log lock from around atomic operation where it is not needed, removes an unused variable, and also changes a void pointer used incorrectly to a struct page pointer. Signed-off-by: Steven Whitehouse

GFS2: Remove bd_list_tr

2012-04-24T15:44:36Z

This is another clean up in the logging code. This per-transaction list was largely unused. Its main function was to ensure that the number of buffers in a transaction was correct, however that counter was only used to check the number of buffers in the bd_list_tr, plus an assert at the end of each transaction. With the assert now changed to use the calculated buffer counts, we can remove both bd_list_tr and its associated counter. This should make the code easier to understand as well as shrinking a couple of structures. Signed-off-by: Steven Whitehouse

GFS2: Clean up log write code path

2012-04-24T15:44:34Z

Prior to this patch, we have two ways of sending i/o to the log. One of those is used when we need to allocate both the data to be written itself and also a buffer head to submit it. This is done via sb_getblk and friends. This is used mostly for writing log headers. The other method is used when writing blocks which have some in-place counterpart. This is the case for all the metadata blocks which are journalled, and when journaled data is in use, for unescaped journalled data blocks. This patch replaces both of those two methods, and about half a dozen separate i/o submission points with a single i/o submission function. We also go direct to bio rather than using buffer heads, since this allows us to build i/o requests of the maximum size for the block device in question. It also reduces the memory required for flushing the log, which can be very useful in low memory situations. Signed-off-by: Steven Whitehouse

GFS2: Drop "pull" argument from log_write_header()

2012-04-24T15:44:24Z

The "pull" argument to log_write_header() is only used for debug purposes and it is not really needed any more. There are other tests for this particular problem, so I think we can dispose of it in order to simplify the code. Signed-off-by: Steven Whitehouse

GFS2: Clean up log flush header writing

2012-03-09T14:07:06Z

We already send both a pre and post flush to the block device when writing a journal header. There is no need to wait for the previous I/O specifically when we do this, unless we've turned "barriers" off. As a side effect, this also cleans up the code path for flushing the journal and makes it more readable. Signed-off-by: Steven Whitehouse