- 23 Aug, 2021 40 commits
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Boris Burkov authored
Currently, inode flags are fully backwards incompatible in btrfs. If we introduce a new inode flag, then tree-checker will detect it and fail. This can even cause us to fail to mount entirely. To make it possible to introduce new flags which can be read-only compatible, like VERITY, we add new ro flags to btrfs without treating them quite so harshly in tree-checker. A read-only file system can survive an unexpected flag, and can be mounted. As for the implementation, it unfortunately gets a little complicated. The on-disk representation of the inode, btrfs_inode_item, has an __le64 for flags but the in-memory representation, btrfs_inode, uses a u32. David Sterba had the nice idea that we could reclaim those wasted 32 bits on disk and use them for the new ro_compat flags. It turns out that the tree-checker code which checks for unknown flags is broken, and ignores the upper 32 bits we are hoping to use. The issue is that the flags use the literal 1 rather than 1ULL, so the flags are signed ints, and one of them is specifically (1 << 31). As a result, the mask which ORs the flags is a negative integer on machines where int is 32 bit twos complement. When tree-checker evaluates the expression: btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK) The mask is something like 0x80000abc, which gets promoted to u64 with sign extension to 0xffffffff80000abc. Negating that 64 bit mask leaves all the upper bits zeroed, and we can't detect unexpected flags. This suggests that we can't use those bits after all. Luckily, we have good reason to believe that they are zero anyway. Inode flags are metadata, which is always checksummed, so any bit flips that would introduce 1s would cause a checksum failure anyway (excluding the improbable case of the checksum getting corrupted exactly badly). Further, unless the 1 << 31 flag is used, the cast to u64 of the 32 bit inode flag should preserve its value and not add leading zeroes (at least for twos complement). The only place that flag (BTRFS_INODE_ROOT_ITEM_INIT) is used is in a special inode embedded in the root item, and indeed for that inode we see 0xffffffff80000000 as the flags on disk. However, that inode is never seen by tree checker, nor is it used in a context where verity might be meaningful. Theoretically, a future ro flag might cause trouble on that inode, so we should proactively clean up that mess before it does. With the introduction of the new ro flags, keep two separate unsigned masks and check them against the appropriate u32. Since we no longer run afoul of sign extension, this also stops writing out 0xffffffff80000000 in root_item inodes going forward. Signed-off-by:
Boris Burkov <boris@bur.io> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
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Anand Jain authored
Function btrfs_check_raid_min_devices() returns error code from the enum btrfs_err_code and it starts from 1. So there is no need to check if ret is > 0. So drop this check and also drop the local variable ret. Signed-off-by:
Anand Jain <anand.jain@oracle.com> Reviewed-by:
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Qu Wenruo authored
When btrfs_run_delalloc_range() failed, we will error out. But there is a strange comment mentioning that btrfs_run_delalloc_range() could have returned value >0 to indicate the IO has already started. Commit 40f76580 ("Btrfs: split up __extent_writepage to lower stack usage") introduced the comment, but unfortunately at that time, we were already using @page_started to indicate that case, and still return 0. Furthermore, even if that comment was right (which is not), we would return -EIO if the IO had already started. By all means the comment is incorrect, just remove the comment along with the dead check. Just to be extra safe, add an ASSERT() in btrfs_run_delalloc_range() to make sure we either return 0 or error, no positive return value. Signed-off-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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David Sterba authored
The data on raid0 and raid10 are supposed to be spread over multiple devices, so the minimum constraints are set to 2 and 4 respectively. This is an artificial limit and there's some interest to remove it. Change this to allow raid0 on one device and raid10 on two devices. This works as expected eg. when converting or removing devices. The only difference is when raid0 on two devices gets one device removed. Unpatched would silently create a single profile, while newly it would be raid0. The motivation is to allow to preserve the profile type as long as it possible for some intermediate state (device removal, conversion), or when there are disks of different size, with raid0 the otherwise unusable space of the last device will be used too. Similarly for raid10, though the two largest devices would need to be the same. Unpatched kernel will mount and use the degenerate profiles just fine but won't allow any operation that would not satisfy the stricter device number constraints, eg. not allowing to go from 3 to 2 devices for raid10 or various profile conversions. Example output: # btrfs fi us -T . Overall: Device size: 10.00GiB Device allocated: 1.01GiB Device unallocated: 8.99GiB Device missing: 0.00B Used: 200.61MiB Free (estimated): 9.79GiB (min: 9.79GiB) Free (statfs, df): 9.79GiB Data ratio: 1.00 Metadata ratio: 1.00 Global reserve: 3.25MiB (used: 0.00B) Multiple profiles: no Data Metadata System Id Path RAID0 single single Unallocated -- ---------- --------- --------- -------- ----------- 1 /dev/sda10 1.00GiB 8.00MiB 1.00MiB 8.99GiB -- ---------- --------- --------- -------- ----------- Total 1.00GiB 8.00MiB 1.00MiB 8.99GiB Used 200.25MiB 352.00KiB 16.00KiB # btrfs dev us . /dev/sda10, ID: 1 Device size: 10.00GiB Device slack: 0.00B Data,RAID0/1: 1.00GiB Metadata,single: 8.00MiB System,single: 1.00MiB Unallocated: 8.99GiB Note "Data,RAID0/1", with btrfs-progs 5.13+ the number of devices per profile is printed. Reviewed-by: -
Filipe Manana authored
During renames we pin the logs of the roots a bit too early, before the calls to btrfs_insert_inode_ref(). We can pin the logs after those calls, since those will not change anything in a log tree. In a scenario where we have multiple and diverse filesystem operations running in parallel, those calls can take a significant amount of time, due to lock contention on extent buffers, and delay log commits from other tasks for longer than necessary. So just pin logs after calls to btrfs_insert_inode_ref() and right before the first operation that can update a log tree. The following script that uses dbench was used for testing: $ cat dbench-test.sh #!/bin/bash DEV=/dev/nvme0n1 MNT=/mnt/nvme0n1 MOUNT_OPTIONS="-o ssd" MKFS_OPTIONS="-m single -d single" echo "performance" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor umount $DEV &> /dev/null mkfs.btrfs -f $MKFS_OPTIONS $DEV mount $MOUNT_OPTIONS $DEV $MNT dbench -D $MNT -t 120 16 umount $MNT The tests were run on a machine with 12 cores, 64G of RAN, a NVMe device and using a non-debug kernel config (Debian's default config). The results compare a branch without this patch and without the previous patch in the series, that has the subject: "btrfs: eliminate some false positives when checking if inode was logged" Versus the same branch with these two patches applied. dbench with 8 clients, results before: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 4391359 0.009 249.745 Close 3225882 0.001 3.243 Rename 185953 0.065 240.643 Unlink 886669 0.049 249.906 Deltree 112 2.455 217.433 Mkdir 56 0.002 0.004 Qpathinfo 3980281 0.004 3.109 Qfileinfo 697579 0.001 0.187 Qfsinfo 729780 0.002 2.424 Sfileinfo 357764 0.004 1.415 Find 1538861 0.016 4.863 WriteX 2189666 0.010 3.327 ReadX 6883443 0.002 0.729 LockX 14298 0.002 0.073 UnlockX 14298 0.001 0.042 Flush 307777 2.447 303.663 Throughput 1149.6 MB/sec 8 clients 8 procs max_latency=303.666 ms dbench with 8 clients, results after: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 4269920 0.009 213.532 Close 3136653 0.001 0.690 Rename 180805 0.082 213.858 Unlink 862189 0.050 172.893 Deltree 112 2.998 218.328 Mkdir 56 0.002 0.003 Qpathinfo 3870158 0.004 5.072 Qfileinfo 678375 0.001 0.194 Qfsinfo 709604 0.002 0.485 Sfileinfo 347850 0.004 1.304 Find 1496310 0.017 5.504 WriteX 2129613 0.010 2.882 ReadX 6693066 0.002 1.517 LockX 13902 0.002 0.075 UnlockX 13902 0.001 0.055 Flush 299276 2.511 220.189 Throughput 1187.33 MB/sec 8 clients 8 procs max_latency=220.194 ms +3.2% throughput, -31.8% max latency dbench with 16 clients, results before: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 5978334 0.028 156.507 Close 4391598 0.001 1.345 Rename 253136 0.241 155.057 Unlink 1207220 0.182 257.344 Deltree 160 6.123 36.277 Mkdir 80 0.003 0.005 Qpathinfo 5418817 0.012 6.867 Qfileinfo 949929 0.001 0.941 Qfsinfo 993560 0.002 1.386 Sfileinfo 486904 0.004 2.829 Find 2095088 0.059 8.164 WriteX 2982319 0.017 9.029 ReadX 9371484 0.002 4.052 LockX 19470 0.002 0.461 UnlockX 19470 0.001 0.990 Flush 418936 2.740 347.902 Throughput 1495.31 MB/sec 16 clients 16 procs max_latency=347.909 ms dbench with 16 clients, results after: Operation Count AvgLat MaxLat ---------------------------------------- NTCreateX 5711833 0.029 131.240 Close 4195897 0.001 1.732 Rename 241849 0.204 147.831 Unlink 1153341 0.184 231.322 Deltree 160 6.086 30.198 Mkdir 80 0.003 0.021 Qpathinfo 5177011 0.012 7.150 Qfileinfo 907768 0.001 0.793 Qfsinfo 949205 0.002 1.431 Sfileinfo 465317 0.004 2.454 Find 2001541 0.058 7.819 WriteX 2850661 0.017 9.110 ReadX 8952289 0.002 3.991 LockX 18596 0.002 0.655 UnlockX 18596 0.001 0.179 Flush 400342 2.879 293.607 Throughput 1565.73 MB/sec 16 clients 16 procs max_latency=293.611 ms +4.6% throughput, -16.9% max latency Signed-off-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
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Filipe Manana authored
When checking if an inode was previously logged in the current transaction through the helper inode_logged(), we can return some false positives that can be easily eliminated. These correspond to the cases where an inode has a ->logged_trans value that is not zero and its value is smaller then the ID of the current transaction. This means we know exactly that the inode was never logged before in the current transaction, so we can return false and avoid the callers to do extra work: 1) Having btrfs_del_dir_entries_in_log() and btrfs_del_inode_ref_in_log() unnecessarily join a log transaction and do deletion searches in a log tree that will not find anything. This just adds unnecessary contention on extent buffer locks; 2) Having btrfs_log_new_name() unnecessarily log an inode when it is not needed. If the inode was not logged before, we don't need to log it in LOG_INODE_EXISTS mode. So just make sure that any false positive only happens when ->logged_trans has a value of 0. Signed-off-by:
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Naohiro Aota authored
When on SINGLE block group, btrfs_get_io_geometry() will return "the size of the block group - the offset of the logical address within the block group" as geom.len. Since we allow up to 8 GiB zone size on zoned filesystem, we can have up to 8 GiB block group, so can have up to 8 GiB geom.len as well. With this setup, we easily hit the "ASSERT(geom.len <= INT_MAX);". The ASSERT looks like to guard btrfs_bio_clone_partial() and bio_trim() which both take "int" (now u64 due to the previous patch). So to be precise the ASSERT should check if clone_len <= UINT_MAX. But actually, clone_len is already capped by bio.bi_iter.bi_size which is unsigned int. So the ASSERT is not necessary. Drop the ASSERT and properly compare submit_len and geom.len in u64. Then, let the implicit casting to convert it to u64. Signed-off-by:
Naohiro Aota <naohiro.aota@wdc.com> Reviewed-by:
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Chaitanya Kulkarni authored
The offset and can never be negative use unsigned int instead of int type for them. Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by:
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Chaitanya Kulkarni authored
The function bio_trim has offset and size arguments that are declared as int. The callers of this function use sector_t type when passing the offset and size, e.g. drivers/md/raid1.c:narrow_write_error() and drivers/md/raid1.c:narrow_write_error(). Change offset and size arguments to sector_t type for bio_trim(). Also, add WARN_ON_ONCE() to catch their overflow. Reviewed-by:
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Josef Bacik authored
Now that all users of sync_inode() have been deleted, remove sync_inode(). Reviewed-by:
Nikolay Borisov <nborisov@suse.com> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
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Josef Bacik authored
We're going to remove sync_inode, so migrate to filemap_fdatawrite_wbc instead. Reviewed-by:
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Josef Bacik authored
sync_inode() has some holes that can cause problems if we're under heavy ENOSPC pressure. If there's writeback running on a separate thread sync_inode() will skip writing the inode altogether. What we really want is to make sure writeback has been started on all the pages to make sure we can see the ordered extents and wait on them if appropriate. Switch to this new helper which will allow us to accomplish this and avoid ENOSPC'ing early. Reviewed-by:
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Josef Bacik authored
Btrfs sometimes needs to flush dirty pages on a bunch of dirty inodes in order to reclaim metadata reservations. Unfortunately most helpers in this area are too smart for us: 1) The normal filemap_fdata* helpers only take range and sync modes, and don't give any indication of how much was written, so we can only flush full inodes, which isn't what we want in most cases. 2) The normal writeback path requires us to have the s_umount sem held, but we can't unconditionally take it in this path because we could deadlock. 3) The normal writeback path also skips inodes with I_SYNC set if we write with WB_SYNC_NONE. This isn't the behavior we want under heavy ENOSPC pressure, we want to actually make sure the pages are under writeback before returning, and if another thread is in the middle of writing the file we may return before they're under writeback and miss our ordered extents and not properly wait for completion. 4) sync_inode() uses the normal writeback path and has the same problem as #3. What we really want is to call do_writepages() with our wbc. This way we can make sure that writeback is actually started on the pages, and we can control how many pages are written as a whole as we write many inodes using the same wbc. Accomplish this with a new helper that does just that so we can use it for our ENOSPC flushing infrastructure. Reviewed-by:
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Josef Bacik authored
I've been debugging an early ENOSPC problem in production and finally root caused it to this problem. When we switched to the per-inode in 38d715f4 ("btrfs: use btrfs_start_delalloc_roots in shrink_delalloc") I pulled out the async extent handling, because we were doing the correct thing by calling filemap_flush() if we had async extents set. This would properly wait on any async extents by locking the page in the second flush, thus making sure our ordered extents were properly set up. However when I switched us back to page based flushing, I used sync_inode(), which allows us to pass in our own wbc. The problem here is that sync_inode() is smarter than the filemap_* helpers, it tries to avoid calling writepages at all. This means that our second call could skip calling do_writepages altogether, and thus not wait on the pagelock for the async helpers. This means we could come back before any ordered extents were created and then simply continue on in our flushing mechanisms and ENOSPC out when we have plenty of space to use. Fix this by putting back the async pages logic in shrink_delalloc. This allows us to bulk write out everything that we need to, and then we can wait in one place for the async helpers to catch up, and then wait on any ordered extents that are created. Fixes: e076ab2a ("btrfs: shrink delalloc pages instead of full inodes") CC: stable@vger.kernel.org # 5.10+ Reviewed-by:
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Josef Bacik authored
We have been hitting some early ENOSPC issues in production with more recent kernels, and I tracked it down to us simply not flushing delalloc as aggressively as we should be. With tracing I was seeing us failing all tickets with all of the block rsvs at or around 0, with very little pinned space, but still around 120MiB of outstanding bytes_may_used. Upon further investigation I saw that we were flushing around 14 pages per shrink call for delalloc, despite having around 2GiB of delalloc outstanding. Consider the example of a 8 way machine, all CPUs trying to create a file in parallel, which at the time of this commit requires 5 items to do. Assuming a 16k leaf size, we have 10MiB of total metadata reclaim size waiting on reservations. Now assume we have 128MiB of delalloc outstanding. With our current math we would set items to 20, and then set to_reclaim to 20 * 256k, or 5MiB. Assuming that we went through this loop all 3 times, for both FLUSH_DELALLOC and FLUSH_DELALLOC_WAIT, and then did the full loop twice, we'd only flush 60MiB of the 128MiB delalloc space. This could leave a fair bit of delalloc reservations still hanging around by the time we go to ENOSPC out all the remaining tickets. Fix this two ways. First, change the calculations to be a fraction of the total delalloc bytes on the system. Prior to this change we were calculating based on dirty inodes so our math made more sense, now it's just completely unrelated to what we're actually doing. Second add a FLUSH_DELALLOC_FULL state, that we hold off until we've gone through the flush states at least once. This will empty the system of all delalloc so we're sure to be truly out of space when we start failing tickets. I'm tagging stable 5.10 and forward, because this is where we started using the page stuff heavily again. This affects earlier kernel versions as well, but would be a pain to backport to them as the flushing mechanisms aren't the same. CC: stable@vger.kernel.org # 5.10+ Reviewed-by:
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Josef Bacik authored
When debugging early enospc problems it was useful to have a tracepoint where we failed all tickets so I could check the state of the enospc counters at failure time to validate my fixes. This adds the tracpoint so you can easily get that information. Reviewed-by:
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Josef Bacik authored
In order to debug delalloc flushing issues I added delalloc_bytes and ordered_bytes to this tracepoint to see if they were non-zero when we were going ENOSPC. This was valuable for me and showed me cases where we weren't waiting on ordered extents properly. In order to add this to the tracepoint we need to take away the const modifier for fs_info, as percpu_sum_counter_positive() will change the counter when it adds up the percpu buckets. This is needed to make sure we're getting accurate information at these tracepoints, as the wrong information could send us down the wrong path when debugging problems. Reviewed-by:
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Josef Bacik authored
We use the async_delalloc_pages mechanism to make sure that we've completed our async work before trying to continue our delalloc flushing. The reason for this is we need to see any ordered extents that were created by our delalloc flushing. However we're waking up before we do the submit work, which is before we create the ordered extents. This is a pretty wide race window where we could potentially think there are no ordered extents and thus exit shrink_delalloc prematurely. Fix this by waking us up after we've done the work to create ordered extents. CC: stable@vger.kernel.org # 5.4+ Reviewed-by:
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Qu Wenruo authored
[BUG] When running btrfs/160 in a loop for subpage with experimental compression support, it has a high chance to crash (~20%): BTRFS critical (device dm-7): panic in __btrfs_add_ordered_extent:238: inconsistency in ordered tree at offset 0 (errno=-17 Object already exists) ------------[ cut here ]------------ kernel BUG at fs/btrfs/ordered-data.c:238! Internal error: Oops - BUG: 0 [#1] SMP pc : __btrfs_add_ordered_extent+0x550/0x670 [btrfs] lr : __btrfs_add_ordered_extent+0x550/0x670 [btrfs] Call trace: __btrfs_add_ordered_extent+0x550/0x670 [btrfs] btrfs_add_ordered_extent+0x2c/0x50 [btrfs] run_delalloc_nocow+0x81c/0x8fc [btrfs] btrfs_run_delalloc_range+0xa4/0x390 [btrfs] writepage_delalloc+0xc0/0x1ac [btrfs] __extent_writepage+0xf4/0x370 [btrfs] extent_write_cache_pages+0x288/0x4f4 [btrfs] extent_writepages+0x58/0xe0 [btrfs] btrfs_writepages+0x1c/0x30 [btrfs] do_writepages+0x60/0x110 __filemap_fdatawrite_range+0x108/0x170 filemap_fdatawrite_range+0x20/0x30 btrfs_fdatawrite_range+0x34/0x4dc [btrfs] __btrfs_write_out_cache+0x34c/0x480 [btrfs] btrfs_write_out_cache+0x144/0x220 [btrfs] btrfs_start_dirty_block_groups+0x3ac/0x6b0 [btrfs] btrfs_commit_transaction+0xd0/0xbb4 [btrfs] btrfs_sync_fs+0x64/0x1cc [btrfs] sync_fs_one_sb+0x3c/0x50 iterate_supers+0xcc/0x1d4 ksys_sync+0x6c/0xd0 __arm64_sys_sync+0x1c/0x30 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0x4c/0xd4 do_el0_svc+0x30/0x9c el0_svc+0x2c/0x54 el0_sync_handler+0x1a8/0x1b0 el0_sync+0x198/0x1c0 ---[ end trace 336f67369ae6e0af ]--- [CAUSE] For subpage case, we can have multiple sectors inside a page, this makes it possible for __extent_writepage() to have part of its page submitted before returning. In btrfs/160, we are using dm-dust to emulate write error, this means for certain pages, we could have everything running fine, but at the end of __extent_writepage(), one of the submitted bios fails due to dm-dust. Then the page is marked Error, and we change @ret from 0 to -EIO. This makes the caller extent_write_cache_pages() to error out, without submitting the remaining pages. Furthermore, since we're erroring out for free space cache, it doesn't really care about the error and will update the inode and retry the writeback. Then we re-run the delalloc range, and will try to insert the same delalloc range while previous delalloc range is still hanging there, triggering the above error. [FIX] The proper fix is to handle errors from __extent_writepage() properly, by ending the remaining ordered extent. But that fix needs the following changes: - Know at exactly which sector the error happened Currently __extent_writepage_io() works for the full page, can't return at which sector we hit the error. - Grab the ordered extent covering the failed sector As a hotfix for subpage case, here we unify the error paths in __extent_writepage(). In fact, the "if (PageError(page))" branch never get executed if @ret is still 0 for non-subpage cases. As for non-subpage case, we never submit current page in __extent_writepage(), but only add current page into bio. The bio can only get submitted in next page. Thus we never get PageError() set due to IO failure, thus when we hit the branch, @ret is never 0. By simply removing that @ret assignment, we let subpage case ignore the IO failure, thus only error out for fatal errors just like regular sectorsize. So that IO error won't be treated as fatal error not trigger the hanging OE problem. Signed-off-by:
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Qu Wenruo authored
Since now we support data and metadata read-write for subpage, remove the RO requirement for subpage mount. There are some extra limitations though: - For now, subpage RW mount is still considered experimental Thus that mount warning will still be there. - No compression support There are still quite some PAGE_SIZE hard coded and quite some call sites use extent_clear_unlock_delalloc() to unlock locked_page. This will screw up subpage helpers. Now for subpage RW mount, no matter what mount option or inode attr is set, all writes will not be compressed. Although reading compressed data has no problem. - No defrag for subpage case The defrag support for subpage case will come in later patches, which will also rework the defrag workflow. - No inline extent will be created This is mostly due to the fact that filemap_fdatawrite_range() will trigger more write than the range specified. In fallocate calls, this behavior can make us to writeback which can be inlined, before we enlarge the i_size. This is a very special corner case, and even current btrfs check won't report error on such inline extent + regular extent. But considering how much effort has been put to prevent such inline + regular, I'd prefer to cut off inline extent completely until we have a good solution. Signed-off-by:
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Qu Wenruo authored
[BUG] When using the following script, btrfs will report data corruption after one data balance with subpage support: mkfs.btrfs -f -s 4k $dev mount $dev -o nospace_cache $mnt $fsstress -w -n 8 -s 1620948986 -d $mnt/ -v > /tmp/fsstress sync btrfs balance start -d $mnt btrfs scrub start -B $mnt Similar problem can be easily observed in btrfs/028 test case, there will be tons of balance failure with -EIO. [CAUSE] Above fsstress will result the following data extents layout in extent tree: item 10 key (13631488 EXTENT_ITEM 98304) itemoff 15889 itemsize 82 refs 2 gen 7 flags DATA extent data backref root FS_TREE objectid 259 offset 1339392 count 1 extent data backref root FS_TREE objectid 259 offset 647168 count 1 item 11 key (13631488 BLOCK_GROUP_ITEM 8388608) itemoff 15865 itemsize 24 block group used 102400 chunk_objectid 256 flags DATA item 12 key (13733888 EXTENT_ITEM 4096) itemoff 15812 itemsize 53 refs 1 gen 7 flags DATA extent data backref root FS_TREE objectid 259 offset 729088 count 1 Then when creating the data reloc inode, the data reloc inode will look like this: 0 32K 64K 96K 100K 104K |<------ Extent A ----->| |<- Ext B ->| Then when we first try to relocate extent A, we setup the data reloc inode with i_size 96K, then read both page [0, 64K) and page [64K, 128K). For page 64K, since the i_size is just 96K, we fill range [96K, 128K) with 0 and set it uptodate. Then when we come to extent B, we update i_size to 104K, then try to read page [64K, 128K). Then we find the page is already uptodate, so we skip the read. But range [96K, 128K) is filled with 0, not the real data. Then we writeback the data reloc inode to disk, with 0 filling range [96K, 128K), corrupting the content of extent B. The behavior is caused by the fact that we still do full page read for subpage case. The bug won't really happen for regular sectorsize, as one page only contains one sector. [FIX] This patch will fix the problem by invalidating range [i_size, PAGE_END] in prealloc_file_extent_cluster(). So that if above example happens, when we preallocate the file extent for extent B, we will clear the uptodate bits for range [96K, 128K), allowing later relocate_one_page() to re-read the needed range. There is a special note for the invalidating part. Since we're not calling real btrfs_invalidatepage(), but just clearing the subpage and page uptodate bits, we can leave a page half dirty and half out of date. Reading such page can cause a deadlock, as we normally expect a dirty page to be fully uptodate. Thus here we flush and wait the data reloc inode before doing the hacked invalidating. This won't cause extra overhead, as we're going to writeback the data later anyway. Reported-by:Ritesh Harjani <riteshh@linux.ibm.com> Signed-off-by:
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Qu Wenruo authored
[BUG] When relocating partial preallocated data extents (part of the preallocated extent is written) for subpage, it can cause the following false alert and make the relocation to fail: BTRFS info (device dm-3): balance: start -d BTRFS info (device dm-3): relocating block group 13631488 flags data BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1 BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 1, gen 0 BTRFS warning (device dm-3): csum failed root -9 ino 257 off 4096 csum 0x98757625 expected csum 0x00000000 mirror 1 BTRFS error (device dm-3): bdev /dev/mapper/arm_nvme-test errs: wr 0, rd 0, flush 0, corrupt 2, gen 0 BTRFS info (device dm-3): balance: ended with status: -5 The minimal script to reproduce looks like this: mkfs.btrfs -f -s 4k $dev mount $dev -o nospace_cache $mnt xfs_io -f -c "falloc 0 8k" $mnt/file xfs_io -f -c "pwrite 0 4k" $mnt/file btrfs balance start -d $mnt [CAUSE] Function btrfs_verify_data_csum() checks if the full range has EXTENT_NODATASUM bit for data reloc inode, if *all* bytes of the range have EXTENT_NODATASUM bit, then it skip the range. This works pretty well for regular sectorsize, as in that case btrfs_verify_data_csum() is called for each sector, thus no problem at all. But for subpage case, btrfs_verify_data_csum() is called on each bvec, which can contain several sectors, and since it checks *all* bytes for EXTENT_NODATASUM bit, if we have some range with csum, then we will continue checking all the sectors. For the preallocated sectors, it doesn't have any csum, thus obviously the csum won't match and cause the false alert. [FIX] Move the EXTENT_NODATASUM check into the main loop, so that we can check each sector for EXTENT_NODATASUM bit for subpage case. Signed-off-by:
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Qu Wenruo authored
[BUG] There is a possible use-after-free bug when running generic/095. BUG: Unable to handle kernel data access on write at 0x6b6b6b6b6b6b725b Faulting instruction address: 0xc000000000283654 c000000000283078 do_raw_spin_unlock+0x88/0x230 c0000000012b1e14 _raw_spin_unlock_irqrestore+0x44/0x90 c000000000a918dc btrfs_subpage_clear_writeback+0xac/0xe0 c0000000009e0458 end_bio_extent_writepage+0x158/0x270 c000000000b6fd14 bio_endio+0x254/0x270 c0000000009fc0f0 btrfs_end_bio+0x1a0/0x200 c000000000b6fd14 bio_endio+0x254/0x270 c000000000b781fc blk_update_request+0x46c/0x670 c000000000b8b394 blk_mq_end_request+0x34/0x1d0 c000000000d82d1c lo_complete_rq+0x11c/0x140 c000000000b880a4 blk_complete_reqs+0x84/0xb0 c0000000012b2ca4 __do_softirq+0x334/0x680 c0000000001dd878 irq_exit+0x148/0x1d0 c000000000016f4c do_IRQ+0x20c/0x240 c000000000009240 hardware_interrupt_common_virt+0x1b0/0x1c0 [CAUSE] There is very small race window like the following in generic/095. Thread 1 | Thread 2 --------------------------------+------------------------------------ end_bio_extent_writepage() | btrfs_releasepage() |- spin_lock_irqsave() | | |- end_page_writeback() | | | | |- if (PageWriteback() ||...) | | |- clear_page_extent_mapped() | | |- kfree(subpage); |- spin_unlock_irqrestore(). The race can also happen between writeback and btrfs_invalidatepage(), although that would be much harder as btrfs_invalidatepage() has much more work to do before the clear_page_extent_mapped() call. [FIX] Here we "wait" for the subapge spinlock to be released before we detach subpage structure. So this patch will introduce a new function, wait_subpage_spinlock(), to do the "wait" by acquiring the spinlock and release it. Since the caller has ensured the page is not dirty nor writeback, and page is already locked, the only way to hold the subpage spinlock is from endio function. Thus we only need to acquire the spinlock to wait for any existing holder. Reported-by:
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Qu Wenruo authored
[BUG] When running generic/095, there is a high chance to crash with subpage data RW support: assertion failed: PagePrivate(page) && page->private ------------[ cut here ]------------ kernel BUG at fs/btrfs/ctree.h:3403! Internal error: Oops - BUG: 0 [#1] SMP CPU: 1 PID: 3567 Comm: fio Tainted: 5.12.0-rc7-custom+ #17 Hardware name: Khadas VIM3 (DT) Call trace: assertfail.constprop.0+0x28/0x2c [btrfs] btrfs_subpage_assert+0x80/0xa0 [btrfs] btrfs_subpage_set_uptodate+0x34/0xec [btrfs] btrfs_page_clamp_set_uptodate+0x74/0xa4 [btrfs] btrfs_dirty_pages+0x160/0x270 [btrfs] btrfs_buffered_write+0x444/0x630 [btrfs] btrfs_direct_write+0x1cc/0x2d0 [btrfs] btrfs_file_write_iter+0xc0/0x160 [btrfs] new_sync_write+0xe8/0x180 vfs_write+0x1b4/0x210 ksys_pwrite64+0x7c/0xc0 __arm64_sys_pwrite64+0x24/0x30 el0_svc_common.constprop.0+0x70/0x140 do_el0_svc+0x28/0x90 el0_svc+0x2c/0x54 el0_sync_handler+0x1a8/0x1ac el0_sync+0x170/0x180 Code: f0000160 913be042 913c4000 955444bc (d4210000) ---[ end trace 3fdd39f4cccedd68 ]--- [CAUSE] Although prepare_pages() calls find_or_create_page(), which returns the page locked, but in later prepare_uptodate_page() calls, we may call btrfs_readpage() which will unlock the page before it returns. This leaves a window where btrfs_releasepage() can sneak in and release the page, clearing page->private and causing above ASSERT(). [FIX] In prepare_uptodate_page(), we should not only check page->mapping, but also PagePrivate() to ensure we are still holding the correct page which has proper fs context setup. Reported-by:
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Qu Wenruo authored
RAID56 is not only unsafe due to its write-hole problem, but also has tons of hardcoded PAGE_SIZE. Disable it for subpage support for now. Reviewed-by:
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Qu Wenruo authored
Current submit_extent_page() just checks if the current page range can be fitted into current bio, and if not, submit then re-add. But this behavior can't handle subpage case at all. For subpage case, the problem is in the page size, 64K, which is also the same size as stripe size. This means, if we can't fit a full 64K into a bio, due to stripe limit, then it won't fit into next bio without crossing stripe either. The proper way to handle it is: - Check how many bytes we can be put into current bio - Put as many bytes as possible into current bio first - Submit current bio - Create a new bio - Add the remaining bytes into the new bio Refactor submit_extent_page() so that it does the above iteration. The main loop inside submit_extent_page() will look like this: cur = pg_offset; while (cur < pg_offset + size) { u32 offset = cur - pg_offset; int added; if (!bio_ctrl->bio) { /* Allocate new bio if needed */ } /* Add as many bytes into the bio */ added = btrfs_bio_add_page(); if (added < size - offset) { /* The current bio is full, submit it */ } cur += added; } Also, since we're doing new bio allocation deep inside the main loop, extract that code into a new helper, alloc_new_bio(). Signed-off-by: -
Qu Wenruo authored
[BUG] When running the following fsx command (extracted from generic/127) on subpage filesystem, it can create inline extent with regular extents: fsx -q -l 262144 -o 65536 -S 191110531 -N 9057 -R -W $mnt/file > /tmp/fsx The offending extent would look like: item 9 key (257 INODE_REF 256) itemoff 15703 itemsize 14 index 2 namelen 4 name: file item 10 key (257 EXTENT_DATA 0) itemoff 14975 itemsize 728 generation 7 type 0 (inline) inline extent data size 707 ram_bytes 707 compression 0 (none) item 11 key (257 EXTENT_DATA 4096) itemoff 14922 itemsize 53 generation 7 type 2 (prealloc) prealloc data disk byte 102346752 nr 4096 prealloc data offset 0 nr 4096 [CAUSE] For subpage filesystem, the writeback is triggered in page units, which means, even if we just want to writeback range [16K, 20K) for 64K page system, we will still try to writeback any dirty sector of range [0, 64K). This is never a problem if sectorsize == PAGE_SIZE, but for subpage, this can cause unexpected problems. For above test case, the last several operations from fsx are: 9055 trunc from 0x40000 to 0x2c3 9057 falloc from 0x164c to 0x19d2 (0x386 bytes) In operation 9055, we dirtied sector [0, 4096), then in falloc, we call btrfs_wait_ordered_range(inode, start=4096, len=4096), only expecting to writeback any dirty data in [4096, 8192), but nothing else. Unfortunately, in subpage case, above btrfs_wait_ordered_range() will trigger writeback of the range [0, 64K), which includes the data at [0, 4096). And since at the call site, we haven't yet increased i_size, which is still 707, this means cow_file_range() can insert an inline extent. Resulting above inline + regular extent. [WORKAROUND] I don't really have any good short-term solution yet, as this means all operations that would trigger writeback need to be reviewed for any i_size change. So here I choose to disable inline extent creation for subpage case as a workaround. We have done tons of work just to avoid such extent, so I don't to create an exception just for subpage. This only affects inline extent creation, subpage has no problem reading existing inline extents at all. Signed-off-by: -
Qu Wenruo authored
[BUG] When running fsstress with subpage RW support, there are random BUG_ON()s triggered with the following trace: kernel BUG at fs/btrfs/file-item.c:667! Internal error: Oops - BUG: 0 [#1] SMP CPU: 1 PID: 3486 Comm: kworker/u13:2 5.11.0-rc4-custom+ #43 Hardware name: Radxa ROCK Pi 4B (DT) Workqueue: btrfs-worker-high btrfs_work_helper [btrfs] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) pc : btrfs_csum_one_bio+0x420/0x4e0 [btrfs] lr : btrfs_csum_one_bio+0x400/0x4e0 [btrfs] Call trace: btrfs_csum_one_bio+0x420/0x4e0 [btrfs] btrfs_submit_bio_start+0x20/0x30 [btrfs] run_one_async_start+0x28/0x44 [btrfs] btrfs_work_helper+0x128/0x1b4 [btrfs] process_one_work+0x22c/0x430 worker_thread+0x70/0x3a0 kthread+0x13c/0x140 ret_from_fork+0x10/0x30 [CAUSE] Above BUG_ON() means there is some bio range which doesn't have ordered extent, which indeed is worth a BUG_ON(). Unlike regular sectorsize == PAGE_SIZE case, in subpage we have extra subpage dirty bitmap to record which range is dirty and should be written back. This means, if we submit bio for a subpage range, we do not only need to clear page dirty, but also need to clear subpage dirty bits. In __extent_writepage_io(), we will call btrfs_page_clear_dirty() for any range we submit a bio. But there is loophole, if we hit a range which is beyond i_size, we just call btrfs_writepage_endio_finish_ordered() to finish the ordered io, then break out, without clearing the subpage dirty. This means, if we hit above branch, the subpage dirty bits are still there, if other range of the page get dirtied and we need to writeback that page again, we will submit bio for the old range, leaving a wild bio range which doesn't have ordered extent. [FIX] Fix it by always calling btrfs_page_clear_dirty() in __extent_writepage_io(). Also to avoid such problem from happening again, add a new assert, btrfs_page_assert_not_dirty(), to make sure both page dirty and subpage dirty bits are cleared before exiting __extent_writepage_io(). Signed-off-by:
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Qu Wenruo authored
For subpage case, one page of data reloc inode can contain several file extents, like this: |<--- File extent A --->| FE B | FE C |<--- File extent D -->| |<--------- Page --------->| We can no longer use PAGE_SIZE directly for various operations. This patch will relocate_one_page() to handle subpage case by: - Iterating through all extents of a cluster when marking pages When marking pages dirty and delalloc, we need to check the cluster extent boundary. Now we introduce a loop to go extent by extent of a page, until we either finished the last extent, or reach the page end. By this, regular sectorsize == PAGE_SIZE can still work as usual, since we will do that loop only once. - Iteration start from max(page_start, extent_start) Since we can have the following case: | FE B | FE C |<--- File extent D -->| |<--------- Page --------->| Thus we can't always start from page_start, but do a max(page_start, extent_start) - Iteration end when the cluster is exhausted Similar to previous case, the last file extent can end before the page end: |<--- File extent A --->| FE B | FE C | |<--------- Page --------->| In this case, we need to manually exit the loop after we have finished the last extent of the cluster. - Reserve metadata space for each extent range Since now we can hit multiple ranges in one page, we should reserve metadata for each range, not simply PAGE_SIZE. Signed-off-by:
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Qu Wenruo authored
In function relocate_file_extent_cluster(), we have a big loop for marking all involved page delalloc. That part is long enough to be contained in one function, so this patch will move that code chunk into a new function, relocate_one_page(). This also provides enough space for later subpage work. Signed-off-by:
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Qu Wenruo authored
For the initial subpage support, although we won't support compressed write, we still need to support compressed read. But for lzo_decompress_bio() it has several problems: - The abuse of PAGE_SIZE for boundary detection For subpage case, we should follow sectorsize to detect the padding zeros. Using PAGE_SIZE will cause subpage compress read to skip certain bytes, and causing read error. - Too many helper variables There are half a dozen helper variables, which is only making things harder to read This patch will rework lzo_decompress_bio() to make it work for subpage: - Use sectorsize to do boundary check, while still use PAGE_SIZE for page switching This allows us to have the same on-disk format for 4K sectorsize fs, while take advantage of larger page size. - Use two main cursors Only @cur_in and @cur_out is utilized as the main cursor. The helper variables will only be declared inside the loop, and only 2 helper variables needed. - Introduce a helper function to copy compressed segment payload Introduce a new helper, copy_compressed_segment(), to copy a compressed segment to workspace buffer. This function will handle the page switching. Now the net result is, with all the excessive comments and new helper function, the refactored code is still smaller, and easier to read. For other decompression code, they have no special padding rule, thus no need to bother for initial subpage support, but will be refactored to the same style later. Signed-off-by:
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Qu Wenruo authored
There are several bugs inside the function btrfs_decompress_buf2page() - @start_byte doesn't take bvec.bv_offset into consideration Thus it can't handle case where the target range is not page aligned. - Too many helper variables There are tons of helper variables, @buf_offset, @current_buf_start, @start_byte, @prev_start_byte, @working_bytes, @bytes. This hurts anyone who wants to read the function. - No obvious main cursor for the iteartion A new problem caused by previous problem. - Comments for parameter list makes no sense Like @buf_start is the offset to @buf, or offset inside the full decompressed extent? (Spoiler alert, the later case) And @total_out acts more like @buf_start + @size_of_buf. The worst is @disk_start. The real meaning of it is the file offset of the full decompressed extent. This patch will rework the whole function by: - Add a proper comment with ASCII art to explain the parameter list - Rework parameter list The old @buf_start is renamed to @decompressed, to show how many bytes are already decompressed inside the full decompressed extent. The old @total_out is replaced by @buf_len, which is the decompressed data size. For old @disk_start and @bio, just pass @compressed_bio in. - Use single main cursor The main cursor will be @cur_file_offset, to show what's the current file offset. Other helper variables will be declared inside the main loop, and only minimal amount of helper variables: * offset_inside_decompressed_buf: The only real helper * copy_start_file_offset: File offset we start memcpy * bvec_file_offset: File offset of current bvec Even with all these extensive comments, the final function is still smaller than the original function, which is definitely a win. Signed-off-by:
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Qu Wenruo authored
[BUG] When subpage compressed read write support is enabled, btrfs/038 always fails with EIO. A simplified script can easily trigger the problem: mkfs.btrfs -f -s 4k $dev mount $dev $mnt -o compress=lzo xfs_io -f -c "truncate 118811" $mnt/foo xfs_io -c "pwrite -S 0x0d -b 39987 92267 39987" $mnt/foo > /dev/null sync btrfs subvolume snapshot -r $mnt $mnt/mysnap1 xfs_io -c "pwrite -S 0x3e -b 80000 200000 80000" $mnt/foo > /dev/null sync xfs_io -c "pwrite -S 0xdc -b 10000 250000 10000" $mnt/foo > /dev/null xfs_io -c "pwrite -S 0xff -b 10000 300000 10000" $mnt/foo > /dev/null sync btrfs subvolume snapshot -r $mnt $mnt/mysnap2 cat $mnt/mysnap2/foo # Above cat will fail due to EIO [CAUSE] The problem is in btrfs_submit_compressed_read(). When it tries to grab the extent map of the read range, it uses the following call: em = lookup_extent_mapping(em_tree, page_offset(bio_first_page_all(bio)), fs_info->sectorsize); The problem is in the page_offset(bio_first_page_all(bio)) part. The offending inode has the following file extent layout item 10 key (257 EXTENT_DATA 131072) itemoff 15639 itemsize 53 generation 8 type 1 (regular) extent data disk byte 13680640 nr 4096 extent data offset 0 nr 4096 ram 4096 extent compression 0 (none) item 11 key (257 EXTENT_DATA 135168) itemoff 15586 itemsize 53 generation 8 type 1 (regular) extent data disk byte 0 nr 0 item 12 key (257 EXTENT_DATA 196608) itemoff 15533 itemsize 53 generation 8 type 1 (regular) extent data disk byte 13676544 nr 4096 extent data offset 0 nr 53248 ram 86016 extent compression 2 (lzo) And the bio passed in has the following parameters: page_offset(bio_first_page_all(bio)) = 131072 bio_first_bvec_all(bio)->bv_offset = 65536 If we use page_offset(bio_first_page_all(bio) without adding bv_offset, we will get an extent map for file offset 131072, not 196608. This means we read uncompressed data from disk, and later decompression will definitely fail. [FIX] Take bv_offset into consideration when trying to grab an extent map. And add an ASSERT() to ensure we're really getting a compressed extent. Thankfully this won't affect anything but subpage, thus we only need to ensure this patch get merged before we enabled basic subpage support. Reviewed-by: -
Qu Wenruo authored
For current subpage support, we only support 64K page size with 4K sector size. This makes compressed readahead less effective, as maximum compressed extent size is only 128K, 2x the page size. On the other hand, the function add_ra_bio_pages() is still assuming sectorsize == PAGE_SIZE, and code change may affect 4K page size systems. So for now, let's disable subpage compressed readahead for now. Signed-off-by:
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Qu Wenruo authored
[BUG] When testing experimental subpage compressed write support, it hits a NULL pointer dereference inside read path: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018 pc : __pi_memcmp+0x28/0x1ec lr : check_data_csum+0xd0/0x274 [btrfs] Call trace: __pi_memcmp+0x28/0x1ec btrfs_verify_data_csum+0xf4/0x244 [btrfs] end_bio_extent_readpage+0x1d0/0x6b0 [btrfs] bio_endio+0x15c/0x1dc end_workqueue_fn+0x44/0x64 [btrfs] btrfs_work_helper+0x74/0x250 [btrfs] process_one_work+0x1d4/0x47c worker_thread+0x180/0x400 kthread+0x11c/0x120 ret_from_fork+0x10/0x30 Code: 54000261 d100044c d343fd8c f8408403 (f8408424) ---[ end trace 9e2c59f33ea40866 ]--- [CAUSE] When reading two compressed extents inside the same page, like the following layout, we trigger above crash: 0 32K 64K |-------|\\\\\\\| | \- Compressed extent (A) \--------- Compressed extent (B) For compressed read, we don't need to populate its io_bio->csum, as we rely on compressed_bio->csum to verify the compressed data, and then copy the decompressed to inode pages. Normally btrfs_verify_data_csum() skip such page by checking and clearing its PageChecked flag But since that flag is still for the full page, when endio for inode page range [0, 32K) gets executed, it clears PageChecked flag for the full page. Then when endio for inode page range [32K, 64K) gets executed, since the page no longer has PageChecked flag, it just continues checking, even though io_bio->csum is NULL. [FIX] Thankfully there are only two users of PageChecked bit: - Cow fixup Since subpage has its own way to trace page dirty (dirty_bitmap) and ordered bit (ordered_bitmap), it should never trigger cow fixup. - Compressed read We can distinguish such read by just checking io_bio->csum. So just check io_bio->csum before doing the verification to avoid such NULL pointer dereference. Signed-off-by:
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Qu Wenruo authored
In btrfs_do_readpage(), we never reset @this_bio_flag after we hit a compressed extent. This is fine, as for PAGE_SIZE == sectorsize case, we can only have one sector for one page, thus @this_bio_flag will only be set at most once. But for subpage case, after hitting a compressed extent, @this_bio_flag will always have EXTENT_BIO_COMPRESSED bit, even we're reading a regular extent. This will lead to various read errors, and causing new ASSERT() in incoming subpage patches, which adds more strict check in btrfs_submit_compressed_read(). Fix it by declaring @this_bio_flag inside the main loop and reset its value for each iteration. Reviewed-by:
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David Sterba authored
Comparators just read the data and thus get const parameters. This should be also preserved by the local variables, update all comparators passed to sort or bsearch. Cleanups: - unnecessary casts are dropped - btrfs_cmp_device_free_bytes is cleaned up to follow the common pattern and 'inline' is dropped as the function address is taken Signed-off-by: -
David Sterba authored
There are two helpers doing the same calculations based on nparity and ncopies. calc_data_stripes can be simplified into one expression, so far we don't have profile with both copies and parity, so there's no effective change. calc_stripe_length should reuse the helper and not repeat the same calculation. Reviewed-by:
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David Sterba authored
The device allocation is split to two functions, but one just calls the other and they're very far in the file. Merge them together. Reviewed-by:
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David Sterba authored
The helper does a simple translation from block group flags to index to the btrfs_raid_array table. There's no apparent reason to inline the function, the translation happens usually once per function and is not called in a loop. Making it a proper function saves quite some binary code (x86_64, release config): text data bss dec hex filename 1164011 19253 14912 1198176 124860 pre/btrfs.ko 1161559 19253 14912 1195724 123ecc post/btrfs.ko DELTA: -2451 Also add the const attribute as there are no side effects, this could help compiler to optimize a few things without the function body. Signed-off-by:
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