kernel/linux.git, branch v3.12.24

Linux 3.12.24

2014-07-04T08:06:59+00:00

xfs: don't perform discard if the given range length is less than block size

2014-07-04T08:06:58+00:00

commit f9fd0135610084abef6867d984e9951c3099950d upstream. For discard operation, we should return EINVAL if the given range length is less than a block size, otherwise it will go through the file system to discard data blocks as the end range might be evaluated to -1, e.g, /xfs7: 9811378176 bytes were trimmed This issue can be triggered via xfstests/generic/288. Also, it seems to get the request queue pointer via bdev_get_queue() instead of the hard code pointer dereference is not a bad thing. Signed-off-by: Jie Liu Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: xfs_remove deadlocks due to inverted AGF vs AGI lock ordering

2014-07-04T08:06:58+00:00

commit 273203699f82667296e1f14344c5a5a6c4600470 upstream. Removing an inode from the namespace involves removing the directory entry and dropping the link count on the inode. Removing the directory entry can result in locking an AGF (directory blocks were freed) and removing a link count can result in placing the inode on an unlinked list which results in locking an AGI. The big problem here is that we have an ordering constraint on AGF and AGI locking - inode allocation locks the AGI, then can allocate a new extent for new inodes, locking the AGF after the AGI. Similarly, freeing the inode removes the inode from the unlinked list, requiring that we lock the AGI first, and then freeing the inode can result in an inode chunk being freed and hence freeing disk space requiring that we lock an AGF. Hence the ordering that is imposed by other parts of the code is AGI before AGF. This means we cannot remove the directory entry before we drop the inode reference count and put it on the unlinked list as this results in a lock order of AGF then AGI, and this can deadlock against inode allocation and freeing. Therefore we must drop the link counts before we remove the directory entry. This is still safe from a transactional point of view - it is not until we get to xfs_bmap_finish() that we have the possibility of multiple transactions in this operation. Hence as long as we remove the directory entry and drop the link count in the first transaction of the remove operation, there are no transactional constraints on the ordering here. Change the ordering of the operations in the xfs_remove() function to align the ordering of AGI and AGF locking to match that of the rest of the code. Signed-off-by: Dave Chinner Reviewed-by: Ben Myers Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: fix the extent count when allocating an new indirection array entry

2014-07-04T08:06:58+00:00

commit bb86d21cba22a045b09d11b71decf5ca7c3d5def upstream. At xfs_iext_add(), if extent(s) are being appended to the last page in the indirection array and the new extent(s) don't fit in the page, the number of extents(erp->er_extcount) in a new allocated entry should be the minimum value between count and XFS_LINEAR_EXTS, instead of count. For now, there is no existing test case can demonstrates a problem with the er_extcount being set incorrectly here, but it obviously like a bug. Signed-off-by: Jie Liu Reviewed-by: Ben Myers Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: fix possible NULL dereference in xlog_verify_iclog

2014-07-04T08:06:57+00:00

commit 643f7c4e5656bd18c769211f933190f7bb738245 upstream. In xlog_verify_iclog a debug check of the incore log buffers prints an error if icptr is null and then goes on to dereference the pointer regardless. Convert this to an assert so that the intention is clear. This was reported by Coverty. Signed-off-by: Ben Myers Reviewed-by: Eric Sandeen Signed-off-by: Jiri Slaby

xfs: prevent stack overflows from page cache allocation

2014-07-04T08:06:56+00:00

commit ad22c7a043c2cc6792820e6c5da699935933e87d upstream. Page cache allocation doesn't always go through ->begin_write and hence we don't always get the opportunity to set the allocation context to GFP_NOFS. Failing to do this means we open up the direct relcaim stack to recurse into the filesystem and consume a significant amount of stack. On RHEL6.4 kernels we are seeing ra_submit() and generic_file_splice_read() from an nfsd context recursing into the filesystem via the inode cache shrinker and evicting inodes. This is causing truncation to be run (e.g EOF block freeing) and causing bmap btree block merges and free space btree block splits to occur. These btree manipulations are occurring with the call chain already 30 functions deep and hence there is not enough stack space to complete such operations. To avoid these specific overruns, we need to prevent the page cache allocation from recursing via direct reclaim. We can do that because the allocation functions take the allocation context from that which is stored in the mapping for the inode. We don't set that right now, so the default is GFP_HIGHUSER_MOVABLE, which is effectively a GFP_KERNEL context. We need it to be the equivalent of GFP_NOFS, so when we initialise an inode, set the mapping gfp mask appropriately. This makes the use of AOP_FLAG_NOFS redundant from other parts of the XFS IO path, so get rid of it. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: don't break from growfs ag update loop on error

2014-07-04T08:06:56+00:00

commit 59e5a0e821d838854b3afd030d31f82cee3ecd58 upstream. When xfs_growfs_data_private() is updating backup superblocks, it bails out on the first error encountered, whether reading or writing: * If we get an error writing out the alternate superblocks, * just issue a warning and continue. The real work is * already done and committed. This can cause a problem later during repair, because repair looks at all superblocks, and picks the most prevalent one as correct. If we bail out early in the backup superblock loop, we can end up with more "bad" matching superblocks than good, and a post-growfs repair may revert the filesystem to the old geometry. With the combination of superblock verifiers and old bugs, we're more likely to encounter read errors due to verification. And perhaps even worse, we don't even properly write any of the newly-added superblocks in the new AGs. Even with this change, growfs will still say: xfs_growfs: XFS_IOC_FSGROWFSDATA xfsctl failed: Structure needs cleaning data blocks changed from 319815680 to 335216640 which might be confusing to the user, but it at least communicates that something has gone wrong, and dmesg will probably highlight the need for an xfs_repair. And this is still best-effort; if verifiers fail on more than half the backup supers, they may still "win" - but that's probably best left to repair to more gracefully handle by doing its own strict verification as part of the backup super "voting." Signed-off-by: Eric Sandeen Acked-by: Dave Chinner Reviewed-by: Mark Tinguely Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: don't emit corruption noise on fs probes

2014-07-04T08:06:55+00:00

commit 31625f28ad7be67701dc4cefcf52087addd88af4 upstream. If we get EWRONGFS due to probing of non-xfs filesystems, there's no need to issue the scary corruption error and backtrace. Signed-off-by: Eric Sandeen Reviewed-by: Mark Tinguely Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: prevent deadlock trying to cover an active log

2014-07-04T08:06:55+00:00

commit 2c6e24ce1aa6b3b147c75d488c2797ee258eb22b upstream. Recent analysis of a deadlocked XFS filesystem from a kernel crash dump indicated that the filesystem was stuck waiting for log space. The short story of the hang on the RHEL6 kernel is this: - the tail of the log is pinned by an inode - the inode has been pushed by the xfsaild - the inode has been flushed to it's backing buffer and is currently flush locked and hence waiting for backing buffer IO to complete and remove it from the AIL - the backing buffer is marked for write - it is on the delayed write queue - the inode buffer has been modified directly and logged recently due to unlinked inode list modification - the backing buffer is pinned in memory as it is in the active CIL context. - the xfsbufd won't start buffer writeback because it is pinned - xfssyncd won't force the log because it sees the log as needing to be covered and hence wants to issue a dummy transaction to move the log covering state machine along. Hence there is no trigger to force the CIL to the log and hence unpin the inode buffer and therefore complete the inode IO, remove it from the AIL and hence move the tail of the log along, allowing transactions to start again. Mainline kernels also have the same deadlock, though the signature is slightly different - the inode buffer never reaches the delayed write lists because xfs_buf_item_push() sees that it is pinned and hence never adds it to the delayed write list that the xfsaild flushes. There are two possible solutions here. The first is to simply force the log before trying to cover the log and so ensure that the CIL is emptied before we try to reserve space for the dummy transaction in the xfs_log_worker(). While this might work most of the time, it is still racy and is no guarantee that we don't get stuck in xfs_trans_reserve waiting for log space to come free. Hence it's not the best way to solve the problem. The second solution is to modify xfs_log_need_covered() to be aware of the CIL. We only should be attempting to cover the log if there is no current activity in the log - covering the log is the process of ensuring that the head and tail in the log on disk are identical (i.e. the log is clean and at idle). Hence, by definition, if there are items in the CIL then the log is not at idle and so we don't need to attempt to cover it. When we don't need to cover the log because it is active or idle, we issue a log force from xfs_log_worker() - if the log is idle, then this does nothing. However, if the log is active due to there being items in the CIL, it will force the items in the CIL to the log and unpin them. In the case of the above deadlock scenario, instead of xfs_log_worker() getting stuck in xfs_trans_reserve() attempting to cover the log, it will instead force the log, thereby unpinning the inode buffer, allowing IO to be issued and complete and hence removing the inode that was pinning the tail of the log from the AIL. At that point, everything will start moving along again. i.e. the xfs_log_worker turns back into a watchdog that can alleviate deadlocks based around pinned items that prevent the tail of the log from being moved... Signed-off-by: Dave Chinner Reviewed-by: Eric Sandeen Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby

xfs: fix the wrong new_size/rnew_size at xfs_iext_realloc_direct()

2014-07-04T08:06:54+00:00

commit 17ec81c15fd022842f9bc947841ba9fb9eb52591 upstream. At xfs_iext_realloc_direct(), the new_size is changed by adding if_bytes if originally the extent records are stored at the inline extent buffer, and we have to switch from it to a direct extent list for those new allocated extents, this is wrong. e.g, Create a file with three extents which was showing as following, xfs_io -f -c "truncate 100m" /xfs/testme for i in $(seq 0 5 10); do offset=$(($i * $((1 << 20)))) xfs_io -c "pwrite $offset 1m" /xfs/testme done Inline ------ irec: if_bytes bytes_diff new_size 1st 0 16 16 2nd 16 16 32 Switching --------- rnew_size 3rd 32 16 48 + 32 = 80 roundup=128 In this case, the desired value of new_size should be 48, and then it will be roundup to 64 and be assigned to rnew_size. However, this issue has been covered by resetting the if_bytes to the new_size which is calculated at the begnning of xfs_iext_add() before leaving out this function, and in turn make the rnew_size correctly again. Hence, this can not be detected via xfstestes. This patch fix above problem and revise the new_size comments at xfs_iext_realloc_direct() to make it more readable. Also, fix the comments while switching from the inline extent buffer to a direct extent list to reflect this change. Signed-off-by: Jie Liu Reviewed-by: Dave Chinner Signed-off-by: Ben Myers Signed-off-by: Jiri Slaby