- 17 Dec, 2018 40 commits
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Hans van Kranenburg authored
Commit 92e222df "btrfs: alloc_chunk: fix DUP stripe size handling" fixed calculating the stripe_size for a new DUP chunk. However, the same calculation reappears a bit later, and that one was not changed yet. The resulting bug that is exposed is that the newly allocated device extents ('stripes') can have a few MiB overlap with the next thing stored after them, which is another device extent or the end of the disk. The scenario in which this can happen is: * The block device for the filesystem is less than 10GiB in size. * The amount of contiguous free unallocated disk space chosen to use for chunk allocation is 20% of the total device size, or a few MiB more or less. An example: - The filesystem device is 7880MiB (max_chunk_size gets set to 788MiB) - There's 1578MiB unallocated raw disk space left in one contiguous piece. In this case stripe_size is first calculated as 789MiB, (half of 1578MiB). Since 789MiB (stripe_size * data_stripes) > 788MiB (max_chunk_size), we enter the if block. Now stripe_size value is immediately overwritten while calculating an adjusted value based on max_chunk_size, which ends up as 788MiB. Next, the value is rounded up to a 16MiB boundary, 800MiB, which is actually more than the value we had before. However, the last comparison fails to detect this, because it's comparing the value with the total amount of free space, which is about twice the size of stripe_size. In the example above, this means that the resulting raw disk space being allocated is 1600MiB, while only a gap of 1578MiB has been found. The second device extent object for this DUP chunk will overlap for 22MiB with whatever comes next. The underlying problem here is that the stripe_size is reused all the time for different things. So, when entering the code in the if block, stripe_size is immediately overwritten with something else. If later we decide we want to have the previous value back, then the logic to compute it was copy pasted in again. With this change, the value in stripe_size is not unnecessarily destroyed, so the duplicated calculation is not needed any more. Signed-off-by:
Hans van Kranenburg <hans.van.kranenburg@mendix.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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Hans van Kranenburg authored
The variable num_bytes is really a way too generic name for a variable in this function. There are a dozen other variables that hold a number of bytes as value. Give it a name that actually describes what it does, which is holding the size of the chunk that we're allocating. Reviewed-by:
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Hans van Kranenburg authored
The variable num_bytes is used to store the chunk length of the chunk that we're allocating. Do not reuse it for something really different in the same function. Reviewed-by:
Nikolay Borisov <nborisov@suse.com> Signed-off-by:
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Ethan Lien authored
Snapshot is expected to be fast. But if there are writers steadily creating dirty pages in our subvolume, the snapshot may take a very long time to complete. To fix the problem, we use tagged writepage for snapshot flusher as we do in the generic write_cache_pages(), so we can omit pages dirtied after the snapshot command. This does not change the semantics regarding which data get to the snapshot, if there are pages being dirtied during the snapshotting operation. There's a sync called before snapshot is taken in old/new case, any IO in flight just after that may be in the snapshot but this depends on other system effects that might still sync the IO. We do a simple snapshot speed test on a Intel D-1531 box: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=write --size=64G --direct=0 --thread=1 --numjobs=1 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 1m58sec patched: 6.54sec This is the best case for this patch since for a sequential write case, we omit nearly all pages dirtied after the snapshot command. For a multi writers, random write test: fio --ioengine=libaio --iodepth=32 --bs=4k --rw=randwrite --size=64G --direct=0 --thread=1 --numjobs=4 --time_based --runtime=120 --filename=/mnt/sub/testfile --name=job1 --group_reporting & sleep 5; time btrfs sub snap -r /mnt/sub /mnt/snap; killall fio original: 15.83sec patched: 10.35sec The improvement is smaller compared to the sequential write case, since we omit only half of the pages dirtied after snapshot command. Reviewed-by:
Ethan Lien <ethanlien@synology.com> Reviewed-by:
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Nikolay Borisov authored
This parameter was never used, yet was part of the interface of the function ever since its introduction as extent_io_ops::writepage_end_io_hook in e6dcd2dc ("Btrfs: New data=ordered implementation"). Now that NULL is passed everywhere as a value for this parameter let's remove it for good. No functional changes. Signed-off-by:
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Nikolay Borisov authored
The only remaining use of the 'epd' argument in writepage_delalloc is to reference the extent_io_tree which was set in extent_writepages. Since it is guaranteed that page->mapping of any page passed to writepage_delalloc (and __extent_writepage as the sole caller) to be equal to that passed in extent_writepages we can directly get the io_tree via the already passed inode (which is also taken from page->mapping->host). No functional changes. Signed-off-by:
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Nikolay Borisov authored
If epd::extent_locked is set then writepage_delalloc terminates. Make this a bit more apparent in the caller by simply bubbling the check up. This enables to remove epd as an argument to writepage_delalloc in a future patch. No functional change. Signed-off-by:
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Nikolay Borisov authored
Before btrfs_map_bio submits all stripe bios it does a number of checks to ensure the device for every stripe is present. However, it doesn't do a DEV_STATE_MISSING check, instead this is relegated to the lower level btrfs_schedule_bio (in the async submission case, sync submission doesn't check DEV_STATE_MISSING at all). Additionally btrfs_schedule_bios does the duplicate device->bdev check which has already been performed in btrfs_map_bio. This patch moves the DEV_STATE_MISSING check in btrfs_map_bio and removes the duplicate device->bdev check. Doing so ensures that no bio cloning/submission happens for both async/sync requests in the face of missing device. This makes the async io submission path slightly shorter in terms of instruction count. No functional changes. Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
Anand Jain <anand.jain@oracle.com> Signed-off-by:
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Anand Jain authored
dev_replace::replace_state has been set to BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED (0) in the same function, So delete the line which sets replace_state = 0; Reviewed-by:
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Filipe Manana authored
The io_err field of struct btrfs_log_ctx is no longer used after the recent simplification of the fast fsync path, where we now wait for ordered extents to complete before logging the inode. We did this in commit b5e6c3e1 ("btrfs: always wait on ordered extents at fsync time") and commit a2120a47 ("btrfs: clean up the left over logged_list usage") removed its last use. Reviewed-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
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Filipe Manana authored
We currently are in a loop finding each range (corresponding to a btree node/leaf) in a log root's extent io tree and then clean it up. This is a waste of time since we are traversing the extent io tree's rb_tree more times then needed (one for a range lookup and another for cleaning it up) without any good reason. We free the log trees when we are in the critical section of a transaction commit (the transaction state is set to TRANS_STATE_COMMIT_DOING), so it's of great convenience to do everything as fast as possible in order to reduce the time we block other tasks from starting a new transaction. So fix this by traversing the extent io tree once and cleaning up all its records in one go while traversing it. Reviewed-by:
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Nikolay Borisov authored
The loop construct in free_extent_buffer was added in 242e18c7 ("Btrfs: reduce lock contention on extent buffer locks") as means of reducing the times the eb lock is taken, the non-last ref count is decremented and lock is released. As the special handling of UNMAPPED extent buffers was removed now there is only one decrement op which is happening for EXTENT_BUFFER_UNMAPPED case. This commit modifies the loop condition so that in case of UNMAPPED buffers the eb's lock is taken only if we are 100% sure the eb is going to be freed by the current executor of the code. Additionally, remove superfluous ref count ops in btrfs test. Signed-off-by:
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Nikolay Borisov authored
Now that the whole of btrfs code has been audited for eb reference count management it's time to remove the hunk in free_extent_buffer that essentially considered the condition "eb->ref == 2 && EXTENT_BUFFER_DUMMY" to equal "eb->ref = 1". Also remove the last location which takes an extra reference count in alloc_test_extent_buffer. Signed-off-by:
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Nikolay Borisov authored
In qgroup_rescan_leaf a copy is made of the target leaf by calling btrfs_clone_extent_buffer. The latter allocates a new buffer and attaches a new set of pages and copies the content of the source buffer. The new scratch buffer is only used to iterate it's items, it's not published anywhere and cannot be accessed by a third party. Hence, it's not necessary to perform any locking on it whatsoever. Furthermore, remove the extra extent_buffer_get call since the new buffer is always allocated with a reference count of 1 which is sufficient here. No functional changes. Signed-off-by:
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Nikolay Borisov authored
When the 2 comparison trees roots are initialised they are private to the function and already have reference counts of 1 each. There is no need to further increment the reference count since the cloned buffers are already accessed via struct btrfs_path. Eventually the 2 paths used for comparison are going to be released, effectively disposing of the cloned buffers. Signed-off-by:
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Nikolay Borisov authored
When a rewound buffer is created it already has a ref count of 1 and the dummy flag set. Then another ref is taken bumping the count to 2. Finally when this buffer is released from btrfs_release_path the extra reference is decremented by the special handling code in free_extent_buffer. However, this special code is in fact redundant sinca ref count of 1 is still correct since the buffer is only accessed via btrfs_path struct. This paves the way forward of removing the special handling in free_extent_buffer. Signed-off-by:
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Nikolay Borisov authored
get_old_root used used only by btrfs_search_old_slot to initialise the path structure. The old root is always a cloned buffer (either via alloc dummy or via btrfs_clone_extent_buffer) and its reference count is 2: 1 from allocation, 1 from extent_buffer_get call in get_old_root. This latter explicit ref count acquire operation is in fact unnecessary since the semantic is such that the newly allocated buffer is handed over to the btrfs_path for lifetime management. Considering this just remove the extra extent_buffer_get in get_old_root. Signed-off-by:
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Nikolay Borisov authored
In iterate_inode_exrefs the eb is cloned via btrfs_clone_extent_buffer which creates a private extent buffer with the dummy flag set and ref count of 1. Then this buffer is locked for reading and its ref count is incremented by 1. Finally it's fed to the passed iterate_irefs_t function. The actual iterate call back is inode_to_path (coming from paths_from_inode) which feeds the eb to btrfs_ref_to_path. In this final function the passed eb is only read by first assigning it to the local eb variable. This variable is only modified in the case another eb was referenced from the passed path that is eb != eb_in check triggers. Considering this there is no point in locking the cloned eb in iterate_inode_refs since it's never being modified and is not published anywhere. Furthermore the cloned eb is completely fine having its ref count be 1. Signed-off-by:
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Nikolay Borisov authored
In iterate_inode_refs the eb is cloned via btrfs_clone_extent_buffer which creates a private extent buffer with the dummy flag set and ref count of 1. Then this buffer is locked for reading and its ref count is incremented by 1. Finally it's fed to the passed iterate_irefs_t function. The actual iterate call back is inode_to_path (coming from paths_from_inode) which feeds the eb to btrfs_ref_to_path. In this final function the passed eb is only read by first assigning it to the local eb variable. This variable is only modified in the case another eb was referenced from the passed path that is eb != eb_in check triggers. Considering this there is no point in locking the cloned eb in iterate_inode_refs since it's never being modified and is not published anywhere. Furthermore the cloned eb is completely fine having its ref count be 1. Signed-off-by:
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Qu Wenruo authored
In extent-io self test, we need 2 ordered extents at its maximum size to do the test. Instead of using the intermediate numbers, use BTRFS_MAX_EXTENT_SIZE for @max_bytes, and twice @max_bytes for @total_dirty. This should explain why we need all these magic numbers and prevent people to modify them by accident. Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Omar Sandoval authored
Btrfs has not allowed swap files since commit 35054394 ("Btrfs: stop providing a bmap operation to avoid swapfile corruptions"). However, now that the proper restrictions are in place, Btrfs can support swap files through the swap file a_ops, similar to iomap in commit 67482129 ("iomap: add a swapfile activation function"). For Btrfs, activation needs to make sure that the file can be used as a swap file, which currently means that it must be fully allocated as NOCOW with no compression on one device. It must also do the proper tracking so that ioctls will not interfere with the swap file. Deactivation clears this tracking. Signed-off-by:
Omar Sandoval <osandov@fb.com> Reviewed-by:
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Omar Sandoval authored
The Btrfs swap code is going to need it, so give it a btrfs_ prefix and make it non-static. Reviewed-by:
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Omar Sandoval authored
A later patch will implement swap file support for Btrfs, but before we do that, we need to make sure that the various Btrfs ioctls cannot change a swap file. When a swap file is active, we must make sure that the extents of the file are not moved and that they don't become shared. That means that the following are not safe: - chattr +c (enable compression) - reflink - dedupe - snapshot - defrag Don't allow those to happen on an active swap file. Additionally, balance, resize, device remove, and device replace are also unsafe if they affect an active swapfile. Add a red-black tree of block groups and devices which contain an active swapfile. Relocation checks each block group against this tree and skips it or errors out for balance or resize, respectively. Device remove and device replace check the tree for the device they will operate on. Note that we don't have to worry about chattr -C (disable nocow), which we ignore for non-empty files, because an active swapfile must be non-empty and can't be truncated. We also don't have to worry about autodefrag because it's only done on COW files. Truncate and fallocate are already taken care of by the generic code. Device add doesn't do relocation so it's not an issue, either. Signed-off-by:
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Nikolay Borisov authored
This is the counterpart to merge_extent_hook, similarly, it's used only for data/freespace inodes so let's remove it, rename it and call it directly where necessary. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This callback is used only for data and free space inodes. Such inodes are guaranteed to have their extent_io_tree::private_data set to the inode struct. Exploit this fact to directly call the function. Also give it a more descriptive name. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This is the counterpart to ex-set_bit_hook (now btrfs_set_delalloc_extent), similar to what was done before remove clear_bit_hook and rename the function. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This callback is used to properly account delalloc extents for data inodes (ordinary file inodes and freespace v1 inodes). Those can be easily identified since they have their extent_io trees ->private_data member point to the inode. Let's exploit this fact to remove the needless indirection through extent_io_hooks and directly call the function. Also give the function a name which reflects its purpose - btrfs_set_delalloc_extent. This patch also modified test_find_delalloc so that the extent_io_tree used for testing doesn't have its ->private_data set which would have caused a crash in btrfs_set_delalloc_extent due to the btrfs_inode->root member not being initialised. The old version of the code also didn't call set_bit_hook since the extent_io ops weren't set for the inode. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This callback was only used in debug builds by btrfs_leak_debug_check. A better approach is to move its implementation in btrfs_leak_debug_check and ensure the latter is only executed for extent tree which have ->private_data set i.e. relate to a data node and not the btree one. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This callback is ony ever called for data page writeout so there is no need to actually abstract it via extent_io_ops. Lets just export it, remove the definition of the callback and call it directly in the functions that invoke the callback. Also rename the function to btrfs_writepage_endio_finish_ordered since what it really does is account finished io in the ordered extent data structures. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This hook is called only from __extent_writepage_io which is already called only from the data page writeout path. So there is no need to make an indirect call via extent_io_ops. This patch just removes the callback definition, exports the callback function and calls it directly at the only call site. Also give the function a more descriptive name. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This callback is called only from writepage_delalloc which in turn is guaranteed to be called from the data page writeout path. In the end there is no reason to have the call to this function to be indrected via the extent_io_ops structure. This patch removes the callback definition, exports the function and calls it directly. No functional changes. Reviewed-by:
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Nikolay Borisov authored
This will be used in future patches that remove the optional extent_io_ops callbacks. Signed-off-by:
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Qu Wenruo authored
Add extra dev extent end check against device boundary. Signed-off-by:
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Qu Wenruo authored
Enhance btrfs_verify_dev_extents() to remember previous checked dev extents, so it can verify no dev extents can overlap. Analysis from Hans: "Imagine allocating a DATA|DUP chunk. In the chunk allocator, we first set... max_stripe_size = SZ_1G; max_chunk_size = BTRFS_MAX_DATA_CHUNK_SIZE ... which is 10GiB. Then... /* we don't want a chunk larger than 10% of writeable space */ max_chunk_size = min(div_factor(fs_devices->total_rw_bytes, 1), max_chunk_size); Imagine we only have one 7880MiB block device in this filesystem. Now max_chunk_size is down to 788MiB. The next step in the code is to search for max_stripe_size * dev_stripes amount of free space on the device, which is in our example 1GiB * 2 = 2GiB. Imagine the device has exactly 1578MiB free in one contiguous piece. This amount of bytes will be put in devices_info[ndevs - 1].max_avail Next we recalculate the stripe_size (which is actually the device extent length), based on the actual maximum amount of available raw disk space: stripe_size = div_u64(devices_info[ndevs - 1].max_avail, dev_stripes); stripe_size is now 789MiB Next we do... data_stripes = num_stripes / ncopies ...where data_stripes ends up as 1, because num_stripes is 2 (the amount of device extents we're going to have), and DUP has ncopies 2. Next there's a check... if (stripe_size * data_stripes > max_chunk_size) ...which matches because 789MiB * 1 > 788MiB. We go into the if code, and next is... stripe_size = div_u64(max_chunk_size, data_stripes); ...which resets stripe_size to max_chunk_size: 788MiB Next is a fun one... /* bump the answer up to a 16MB boundary */ stripe_size = round_up(stripe_size, SZ_16M); ...which changes stripe_size from 788MiB to 800MiB. We're not done changing stripe_size yet... /* But don't go higher than the limits we found while searching * for free extents */ stripe_size = min(devices_info[ndevs - 1].max_avail, stripe_size); This is bad. max_avail is twice the stripe_size (we need to fit 2 device extents on the same device for DUP). The result here is that 800MiB < 1578MiB, so it's unchanged. However, the resulting DUP chunk will need 1600MiB disk space, which isn't there, and the second dev_extent might extend into the next thing (next dev_extent? end of device?) for 22MiB. The last shown line of code relies on a situation where there's twice the value of stripe_size present as value for the variable stripe_size when it's DUP. This was actually the case before commit 92e222df "btrfs: alloc_chunk: fix DUP stripe size handling", from which I quote: "[...] in the meantime there's a check to see if the stripe_size does not exceed max_chunk_size. Since during this check stripe_size is twice the amount as intended, the check will reduce the stripe_size to max_chunk_size if the actual correct to be used stripe_size is more than half the amount of max_chunk_size." In the previous version of the code, the 16MiB alignment (why is this done, by the way?) would result in a 50% chance that it would actually do an 8MiB alignment for the individual dev_extents, since it was operating on double the size. Does this matter? Does it matter that stripe_size can be set to anything which is not 16MiB aligned because of the amount of remaining available disk space which is just taken? What is the main purpose of this round_up? The most straightforward thing to do seems something like... stripe_size = min( div_u64(devices_info[ndevs - 1].max_avail, dev_stripes), stripe_size ) ..just putting half of the max_avail into stripe_size." Link: https://lore.kernel.org/linux-btrfs/b3461a38-e5f8-f41d-c67c-2efac8129054@mendix.com/Reported-by: -
Qu Wenruo authored
We have a complex loop design for find_free_extent(), that has different behavior for each loop, some even includes new chunk allocation. Instead of putting such a long code into find_free_extent() and makes it harder to read, just extract them into find_free_extent_update_loop(). With all the cleanups, the main find_free_extent() should be pretty barebone: find_free_extent() |- Iterate through all block groups | |- Get a valid block group | |- Try to do clustered allocation in that block group | |- Try to do unclustered allocation in that block group | |- Check if the result is valid | | |- If valid, then exit | |- Jump to next block group | |- Push harder to find free extents |- If not found, re-iterate all block groups Signed-off-by:
Su Yue <suy.fnst@cn.fujitsu.com> [ copy callchain from changelog to function comment ] Signed-off-by:
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Qu Wenruo authored
This patch will extract unclsutered extent allocation code into find_free_extent_unclustered(). And this helper function will use return value to indicate what to do next. This should make find_free_extent() a little easier to read. Signed-off-by:
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Qu Wenruo authored
We have two main methods to find free extents inside a block group: 1) clustered allocation 2) unclustered allocation This patch will extract the clustered allocation into find_free_extent_clustered() to make it a little easier to read. Instead of jumping between different labels in find_free_extent(), the helper function will use return value to indicate different behavior. Signed-off-by:
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Qu Wenruo authored
Instead of tons of different local variables in find_free_extent(), extract them into find_free_extent_ctl structure, and add better explanation for them. Some modification may looks redundant, but will later greatly simplify function parameter list during find_free_extent() refactor. Also add two comments to co-operate with fb5c39d7 ("btrfs: don't use ctl->free_space for max_extent_size"), to make ffe_ctl->max_extent_size update more reader-friendly. Signed-off-by:
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Lu Fengqi authored
Introduce a new wrapper update_bytes_pinned to replace open coded bytes_pinned modifiers. Now the underflows of space_info::bytes_pinned get detected and reported. Reviewed-by:
Lu Fengqi <lufq.fnst@cn.fujitsu.com> Signed-off-by:
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Qu Wenruo authored
Although we have space_info::bytes_may_use underflow detection in btrfs_free_reserved_data_space_noquota(), we have more callers who are subtracting number from space_info::bytes_may_use. So instead of doing underflow detection for every caller, introduce a new wrapper update_bytes_may_use() to replace open coded bytes_may_use modifiers. This also introduce a macro to declare more wrappers, but currently space_info::bytes_may_use is the mostly interesting one. Reviewed-by:
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