- 12 Oct, 2023 40 commits
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Filipe Manana authored
There's no need to use WARN() at btrfs_mark_buffer_dirty() to print an error message, as we have the fs_info pointer we can use btrfs_crit() which prints device information and makes the message have a more uniform format. As we are already aborting the transaction we already have a stack trace printed as well. So replace the use of WARN() with btrfs_crit(). Also slightly reword the message to use 'logical' instead of 'block' as it's what is used in other error/warning messages. Signed-off-by:
Filipe Manana <fdmanana@suse.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
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Filipe Manana authored
When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(), we check if its generation matches the running transaction and if not we just print a warning. Such mismatch is an indicator that something really went wrong and only printing a warning message (and stack trace) is not enough to prevent a corruption. Allowing a transaction to commit with such an extent buffer will trigger an error if we ever try to read it from disk due to a generation mismatch with its parent generation. So abort the current transaction with -EUCLEAN if we notice a generation mismatch. For this we need to pass a transaction handle to btrfs_mark_buffer_dirty() which is always available except in test code, in which case we can pass NULL since it operates on dummy extent buffers and all test roots have a single node/leaf (root node at level 0). Signed-off-by:
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Anand Jain authored
After the commit 5f58d783 ("btrfs: free device in btrfs_close_devices for a single device filesystem") we unregister the device from the kernel memory upon unmounting for a single device. So, device registration that was performed before mounting if any is no longer in the kernel memory. However, in fact, note that device registration is unnecessary for a single-device btrfs filesystem unless it's a seed device. So for commands like 'btrfs device scan' or 'btrfs device ready' with a non-seed single-device btrfs filesystem, they can return success just after superblock verification and without the actual device scan. When 'device scan --forget' is called on such device no error is returned. The seed device must remain in the kernel memory to allow the sprout device to mount without the need to specify the seed device explicitly. Signed-off-by:
Anand Jain <anand.jain@oracle.com> Reviewed-by:
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David Sterba authored
We sync the kernel files to userspace and the 'errno' symbol is defined by standard library, which does not matter in kernel but the parameters or local variables could clash. Rename them all. Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Filipe Manana authored
When starting a transaction (or joining an existing one with btrfs_start_transaction()), we reserve space for the number of items we want to insert in a btree, but we don't do it for the delayed refs we will generate while using the transaction to modify (COW) extent buffers in a btree or allocate new extent buffers. Basically how it works: 1) When we start a transaction we reserve space for the number of items the caller wants to be inserted/modified/deleted in a btree. This space goes to the transaction block reserve; 2) If the delayed refs block reserve is not full, its size is greater than the amount of its reserved space, and the flush method is BTRFS_RESERVE_FLUSH_ALL, then we attempt to reserve more space for it corresponding to the number of items the caller wants to insert/modify/delete in a btree; 3) The size of the delayed refs block reserve is increased when a task creates delayed refs after COWing an extent buffer, allocating a new one or deleting (freeing) an extent buffer. This happens after the the task started or joined a transaction, whenever it calls btrfs_update_delayed_refs_rsv(); 4) The delayed refs block reserve is then refilled by anyone calling btrfs_delayed_refs_rsv_refill(), either during unlink/truncate operations or when someone else calls btrfs_start_transaction() with a 0 number of items and flush method BTRFS_RESERVE_FLUSH_ALL; 5) As a task COWs or allocates extent buffers, it consumes space from the transaction block reserve. When the task releases its transaction handle (btrfs_end_transaction()) or it attempts to commit the transaction, it releases any remaining space in the transaction block reserve that it did not use, as not all space may have been used (due to pessimistic space calculation) by calling btrfs_block_rsv_release() which will try to add that unused space to the delayed refs block reserve (if its current size is greater than its reserved space). That transferred space may not be enough to completely fulfill the delayed refs block reserve. Plus we have some tasks that will attempt do modify as many leaves as they can before getting -ENOSPC (and then reserving more space and retrying), such as hole punching and extent cloning which call btrfs_replace_file_extents(). Such tasks can generate therefore a high number of delayed refs, for both metadata and data (we can't know in advance how many file extent items we will find in a range and therefore how many delayed refs for dropping references on data extents we will generate); 6) If a transaction starts its commit before the delayed refs block reserve is refilled, for example by the transaction kthread or by someone who called btrfs_join_transaction() before starting the commit, then when running delayed references if we don't have enough reserved space in the delayed refs block reserve, we will consume space from the global block reserve. Now this doesn't make a lot of sense because: 1) We should reserve space for delayed references when starting the transaction, since we have no guarantees the delayed refs block reserve will be refilled; 2) If no refill happens then we will consume from the global block reserve when running delayed refs during the transaction commit; 3) If we have a bunch of tasks calling btrfs_start_transaction() with a number of items greater than zero and at the time the delayed refs reserve is full, then we don't reserve any space at btrfs_start_transaction() for the delayed refs that will be generated by a task, and we can therefore end up using a lot of space from the global reserve when running the delayed refs during a transaction commit; 4) There are also other operations that result in bumping the size of the delayed refs reserve, such as creating and deleting block groups, as well as the need to update a block group item because we allocated or freed an extent from the respective block group; 5) If we have a significant gap between the delayed refs reserve's size and its reserved space, two very bad things may happen: 1) The reserved space of the global reserve may not be enough and we fail the transaction commit with -ENOSPC when running delayed refs; 2) If the available space in the global reserve is enough it may result in nearly exhausting it. If the fs has no more unallocated device space for allocating a new block group and all the available space in existing metadata block groups is not far from the global reserve's size before we started the transaction commit, we may end up in a situation where after the transaction commit we have too little available metadata space, and any future transaction commit will fail with -ENOSPC, because although we were able to reserve space to start the transaction, we were not able to commit it, as running delayed refs generates some more delayed refs (to update the extent tree for example) - this includes not even being able to commit a transaction that was started with the goal of unlinking a file, removing an empty data block group or doing reclaim/balance, so there's no way to release metadata space. In the worst case the next time we mount the filesystem we may also fail with -ENOSPC due to failure to commit a transaction to cleanup orphan inodes. This later case was reported and hit by someone running a SLE (SUSE Linux Enterprise) distribution for example - where the fs had no more unallocated space that could be used to allocate a new metadata block group, and the available metadata space was about 1.5M, not enough to commit a transaction to cleanup an orphan inode (or do relocation of data block groups that were far from being full). So improve on this situation by always reserving space for delayed refs when calling start_transaction(), and if the flush method is BTRFS_RESERVE_FLUSH_ALL, also try to refill the delayed refs block reserve if it's not full. The space reserved for the delayed refs is added to a local block reserve that is part of the transaction handle, and when a task updates the delayed refs block reserve size, after creating a delayed ref, the space is transferred from that local reserve to the global delayed refs reserve (fs_info->delayed_refs_rsv). In case the local reserve does not have enough space, which may happen for tasks that generate a variable and potentially large number of delayed refs (such as the hole punching and extent cloning cases mentioned before), we transfer any available space and then rely on the current behaviour of hoping some other task refills the delayed refs reserve or fallback to the global block reserve. Reviewed-by:Josef Bacik <josef@toxicpanda.com> Signed-off-by:
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Filipe Manana authored
Currently when reserving space for deleting the csum items for a data extent, when adding or updating a delayed ref head, we determine how many leaves of csum items we can have and then pass that number to the helper btrfs_calc_delayed_ref_bytes(). This helper is used for calculating space for all tree modifications we need when running delayed references, however the amount of space it computes is excessive for deleting csum items because: 1) It uses btrfs_calc_insert_metadata_size() which is excessive because we only need to delete csum items from the csum tree, we don't need to insert any items, so btrfs_calc_metadata_size() is all we need (as it computes space needed to delete an item); 2) If the free space tree is enabled, it doubles the amount of space, which is pointless for csum deletion since we don't need to touch the free space tree or any other tree other than the csum tree. So improve on this by tracking how many csum deletions we have and using a new helper to calculate space for csum deletions (just a wrapper around btrfs_calc_metadata_size() with a comment). This reduces the amount of space we need to reserve for csum deletions by a factor of 4, and it helps reduce the number of times we have to block space reservations and have the reclaim task enter the space flushing algorithm (flush delayed items, flush delayed refs, etc) in order to satisfy tickets. For example this results in a total time decrease when unlinking (or truncating) files with many extents, as we end up having to block on space metadata reservations less often. Example test: $ cat test.sh #!/bin/bash DEV=/dev/nullb0 MNT=/mnt/test umount $DEV &> /dev/null mkfs.btrfs -f $DEV # Use compression to quickly create files with a lot of extents # (each with a size of 128K). mount -o compress=lzo $DEV $MNT # 100G gives at least 983040 extents with a size of 128K. xfs_io -f -c "pwrite -S 0xab -b 1M 0 120G" $MNT/foobar # Flush all delalloc and clear all metadata from memory. umount $MNT mount -o compress=lzo $DEV $MNT start=$(date +%s%N) rm -f $MNT/foobar end=$(date +%s%N) dur=$(( (end - start) / 1000000 )) echo "rm took $dur milliseconds" umount $MNT Before this change rm took: 7504 milliseconds After this change rm took: 6574 milliseconds (-12.4%) Reviewed-by:
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Filipe Manana authored
There's no point in initializing to 0 the local variable 'released' as we don't use it before the next assignment to it. So remove the initialization. This may help avoid some warnings with clang tools such as the one reported/fixed by commit 966de47f ("btrfs: remove redundant initialization of variables in log_new_ancestors"). Reviewed-by:
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Filipe Manana authored
Currently when reserving space for delayed refs we do it on a per ref head basis. This is generally enough because most back refs for an extent end up being inlined in the extent item - with the default leaf size of 16K we can have at most 33 inline back refs (this is calculated by the macro BTRFS_MAX_EXTENT_ITEM_SIZE()). The amount of bytes reserved for each ref head is given by btrfs_calc_delayed_ref_bytes(), which basically corresponds to a single path for insertion into the extent tree plus another path for insertion into the free space tree if it's enabled. However if we have reached the limit of inline refs or we have a mix of inline and non-inline refs, then we will need to insert a non-inline ref and update the existing extent item to update the total number of references for the extent. This implies we need reserved space for two insertion paths in the extent tree, but we only reserved for one path. The extent item and the non-inline ref item may be located in different leaves, or even if they are located in the same leaf, after updating the extent item and before inserting the non-inline ref item, the extent buffers in the btree path may have been written (due to memory pressure for e.g.), in which case we need to COW the entire path again. In this case since we have not reserved enough space for the delayed refs block reserve, we will use the global block reserve. If we are in a situation where the fs has no more unallocated space enough to allocate a new metadata block group and available space in the existing metadata block groups is close to the maximum size of the global block reserve (512M), we may end up consuming too much of the free metadata space to the point where we can't commit any future transaction because it will fail, with -ENOSPC, during its commit when trying to allocate an extent for some COW operation (running delayed refs generated by running delayed refs or COWing the root tree's root node at commit_cowonly_roots() for example). Such dramatic scenario can happen if we have many delayed refs that require the insertion of non-inline ref items, due to too many reflinks or snapshots. We also have situations where we use the global block reserve because we could not in advance know that we will need space to update some trees (block group creation for example), so this all adds up to increase the chances of exhausting the global block reserve and making any future transaction commit to fail with -ENOSPC and turn the fs into RO mode, or fail the mount operation in case the mount needs to start and commit a transaction, such as when we have orphans to cleanup for example - such case was reported and hit by someone running a SLE (SUSE Linux Enterprise) distribution for example - where the fs had no more unallocated space that could be used to allocate a new metadata block group, and the available metadata space was about 1.5M, not enough to commit a transaction to cleanup an orphan inode (or do relocation of data block groups that were far from being full). So reserve space for delayed refs by individual refs and not by ref heads, as we may need to COW multiple extent tree paths due to non-inline ref items. Reviewed-by:
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Filipe Manana authored
When running delayed references, through btrfs_run_delayed_refs(), we can specify how many to run, run all existing delayed references and keep running delayed references while we can find any. This is controlled with the value of the 'count' argument, where a value of 0 means to run all delayed references that exist by the time btrfs_run_delayed_refs() is called, (unsigned long)-1 means to keep running delayed references while we are able find any, and any other value to run that exact number of delayed references. Typically a specific value other than 0 or -1 is used when flushing space to try to release a certain amount of bytes for a ticket. In this case we just simply calculate how many delayed reference heads correspond to a specific amount of bytes, with calc_delayed_refs_nr(). However that only takes into account the space reserved for the reference heads themselves, and does not account for the space reserved for deleting checksums from the csum tree (see add_delayed_ref_head() and update_existing_head_ref()) in case we are going to delete a data extent. This means we may end up running more delayed references than necessary in case we process delayed references for deleting a data extent. So change the logic of btrfs_run_delayed_refs() to take a bytes argument to specify how many bytes of delayed references to run/release, using the special values of 0 to mean all existing delayed references and U64_MAX (or (u64)-1) to keep running delayed references while we can find any. This prevents running more delayed references than necessary, when we have delayed references for deleting data extents, but also makes the upcoming changes/patches simpler and it's preparatory work for them. Reviewed-by:
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Filipe Manana authored
At lookup_inline_extent_backref() we can simplify the check for an overrun of the extent item by making the while loop's condition to be "ptr < end" and then check after the loop if an overrun happened ("ptr > end"). This reduces indentation and makes the loop condition more clear. So move the check out of the loop and change the loop condition accordingly, while also adding the 'unlikely' tag to the check since it's not supposed to be triggered. Reviewed-by: -
Filipe Manana authored
At lookup_inline_extent_backref() when trying to insert an inline backref, if we don't find the extent item we log an error and then return -EIO. This error code is confusing because there was actually no IO error, and this means we have some corruption, either caused by a bug or something like a memory bitflip for example. So change the error code from -EIO to -EUCLEAN. Reviewed-by:
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Filipe Manana authored
At lookup_inline_extent_backref(), instead of using a 'ret' and an 'err' variable for tracking the return value, use a single one ('ret'). This simplifies the code, makes it comply with most of the existing code and it's less prone for logic errors as time has proven over and over in the btrfs code. Reviewed-by: -
Filipe Manana authored
Instead of using a 'ret' and an 'err' variable at run_delayed_extent_op() for tracking the return value, use a single one ('ret'). This simplifies the code, makes it comply with most of the existing code and it's less prone for logic errors as time has proven over and over in the btrfs code. Reviewed-by: -
Filipe Manana authored
The 'ref_root' variable, at run_delayed_data_ref(), is not really needed as we can always use ref->root directly, plus its initialization to 0 is completely pointless as we assign it ref->root before its first use. So just drop that variable and use ref->root directly. This may help avoid some warnings with clang tools such as the one reported/fixed by commit 966de47f ("btrfs: remove redundant initialization of variables in log_new_ancestors"). Reviewed-by:
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Filipe Manana authored
At run_delayed_data_ref() we are always initializing a key but the key is only needed and used if we are inserting a new extent. So move the declaration and initialization of the key to 'if' branch where it's used. Also rename the key from 'ins' to 'key', as it's a more clear name. Reviewed-by:
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Filipe Manana authored
Currently the 'refs_to_drop' argument of __btrfs_free_extent() always matches the value of node->ref_mod, so remove the argument and use node->ref_mod at __btrfs_free_extent(). Reviewed-by:
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Filipe Manana authored
Currently the 'refs_to_add' argument of __btrfs_inc_extent_ref() always matches the value of node->ref_mod, so remove the argument and use node->ref_mod at __btrfs_inc_extent_ref(). Reviewed-by:
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Filipe Manana authored
At btrfs_put_delayed_ref(), it's pointless to have a WARN_ON() to check if the refcount of the delayed ref is zero. Such check is already done by the refcount_t module and refcount_dec_and_test(), which loudly complains if we try to decrement a reference count that is currently 0. The WARN_ON() dates back to the time when used a regular atomic_t type for the reference counter, before we switched to the refcount_t type. The main goal of the refcount_t type/module is precisely to catch such types of bugs and loudly complain if they happen. This also reduces a bit the module's text size. Before this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1612483 167145 16864 1796492 1b698c fs/btrfs/btrfs.ko After this change: $ size fs/btrfs/btrfs.ko text data bss dec hex filename 1612371 167073 16864 1796308 1b68d4 fs/btrfs/btrfs.ko Reviewed-by: -
Filipe Manana authored
When running delayed references, at btrfs_run_delayed_refs(), we have this logic to run any new delayed references that might have been added just after we ran all delayed references. This logic grabs the first delayed reference, then locks it to wait for any contention on it before running all new delayed references. This however is pointless and not necessary because at __btrfs_run_delayed_refs() when we start running delayed references, we pick the first reference with btrfs_obtain_ref_head() and then we will lock it (with btrfs_delayed_ref_lock()). So remove the duplicate and unnecessary logic at btrfs_run_delayed_refs(). Reviewed-by:
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Filipe Manana authored
We are passing a block reserve argument to btrfs_reserve_metadata_bytes() which is not really used, all we need is to pass the space_info associated to the block reserve, we don't change the block reserve at all. Not only it's pointless to pass the block reserve, it's also confusing as one might think that the reserved bytes will end up being added to the passed block reserve, when that's not the case. The pattern for reserving space and adding it to a block reserve is to first reserve space with btrfs_reserve_metadata_bytes() and if that succeeds, then add the space to a block reserve by calling btrfs_block_rsv_add_bytes(). Also the reverse of btrfs_reserve_metadata_bytes(), which is btrfs_space_info_free_bytes_may_use(), takes a space_info argument and not a block reserve, so one more reason to pass a space_info and not a block reserve to btrfs_reserve_metadata_bytes(). So change btrfs_reserve_metadata_bytes() and its callers to pass a space_info argument instead of a block reserve argument. Reviewed-by:
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Qu Wenruo authored
The parameter @need_raid_map is mostly a legacy from the old days where we don't yet have a solid definition on the @mirror_num, and only check-integrity was using that parameter, while all other call sites just pass 1 for that parameter. Now since we have removed check-integrity functionality, we can also remove the @need_raid_map parameter. This change will also remove the ability to read P/Q stripe directly when passing 0 as @need_raid_map. Signed-off-by:
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Qu Wenruo authored
Since all check-integrity entry points have been removed, let's also remove the config and all related code relying on that. And since we have removed the mount option for check-integrity, we also need to re-number all the BTRFS_MOUNT_* enums. Signed-off-by:
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Qu Wenruo authored
The function btrfsic_mount() is part of the deprecated check-integrity functionality. Now let's remove the main entry point of check-integrity, and thankfully most of the check-integrity code is self-contained inside check-integrity.c, we can safely remove the function without huge changes to btrfs code base. Signed-off-by:
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Qu Wenruo authored
The function btrfsic_mount() is part of the deprecated check-integrity functionality. Now let's remove the main entry point of check-integrity, and thankfully most of the check-integrity code is self-contained inside check-integrity.c, we can safely remove the function without huge changes to btrfs code base. Signed-off-by:
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Qu Wenruo authored
The function btrfsic_check_bio() is part of the deprecated check-integrity functionality. Now let's remove the main entry point of check-integrity, and thankfully most of the check-integrity code is self-contained inside check-integrity.c, we can safely remove the function without huge changes to btrfs code base. Signed-off-by:
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David Sterba authored
The lock_owner is used for a rare corruption case and we haven't seen any reports in years. Move it to the debugging section of eb. To close the holes also move log_index so the final layout looks like: struct extent_buffer { u64 start; /* 0 8 */ long unsigned int len; /* 8 8 */ long unsigned int bflags; /* 16 8 */ struct btrfs_fs_info * fs_info; /* 24 8 */ spinlock_t refs_lock; /* 32 4 */ atomic_t refs; /* 36 4 */ int read_mirror; /* 40 4 */ s8 log_index; /* 44 1 */ /* XXX 3 bytes hole, try to pack */ struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */ /* --- cacheline 1 boundary (64 bytes) --- */ struct rw_semaphore lock; /* 64 40 */ struct page * pages[16]; /* 104 128 */ /* size: 232, cachelines: 4, members: 11 */ /* sum members: 229, holes: 1, sum holes: 3 */ /* forced alignments: 1, forced holes: 1, sum forced holes: 3 */ /* last cacheline: 40 bytes */ } __attribute__((__aligned__(8))); This saves 8 bytes in total and still keeps the lock on a separate cacheline. Reviewed-by: -
David Sterba authored
We can reduce two members' size that in turn reduce size of struct btrfs_ref from 64 to 56 bytes. As the structure is often used as a local variable several functions reduce their stack usage. - make enum btrfs_ref_type packed, there are only 4 values - switch action and its values to a packed enum Final structure layout: struct btrfs_ref { enum btrfs_ref_type type; /* 0 1 */ enum btrfs_delayed_ref_action action; /* 1 1 */ bool skip_qgroup; /* 2 1 */ /* XXX 5 bytes hole, try to pack */ u64 bytenr; /* 8 8 */ u64 len; /* 16 8 */ u64 parent; /* 24 8 */ union { struct btrfs_data_ref data_ref; /* 32 24 */ struct btrfs_tree_ref tree_ref; /* 32 16 */ }; /* 32 24 */ /* size: 56, cachelines: 1, members: 7 */ /* sum members: 51, holes: 1, sum holes: 5 */ /* last cacheline: 56 bytes */ }; Reviewed-by: -
David Sterba authored
Currently the compression type values are bounded and fit to an u8, we can pack the btrfs_inode a bit by reordering them to the space created by the location key. This reduces size from 1112 to 1104. Reviewed-by:
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David Sterba authored
The values of level are bounded and fit into a byte so let's use it for the structure to reduce size from 88 to 80 bytes on a release build, which increases number of objects in the default 8K slab from 93 to 102. struct prelim_ref { struct rb_node rbnode __attribute__((__aligned__(8))); /* 0 24 */ u64 root_id; /* 24 8 */ struct btrfs_key key_for_search; /* 32 17 */ u8 level; /* 49 1 */ /* XXX 2 bytes hole, try to pack */ int count; /* 52 4 */ struct extent_inode_elem * inode_list; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ u64 parent; /* 64 8 */ u64 wanted_disk_byte; /* 72 8 */ /* size: 80, cachelines: 2, members: 8 */ /* sum members: 78, holes: 1, sum holes: 2 */ /* forced alignments: 1 */ /* last cacheline: 16 bytes */ } __attribute__((__aligned__(8))); Reviewed-by: -
David Sterba authored
There are two helpers to increase used bytes of root items that add or subtract one node size, we don't need to pass the argument for that. Rename the function so it matches the root item member that gets changed. Reviewed-by:
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David Sterba authored
Both callers of btrfs_pin_extent_for_log_replay expand the parameters to extent buffer members. We can simply pass the extent buffer instead. Reviewed-by:
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David Sterba authored
There is only one caller of btrfs_pin_reserved_extent that expands the parameters to extent buffer members. We can simply pass the extent buffer instead. Reviewed-by:
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David Sterba authored
Drop all __must_check annotations because they're used in random functions and not consistently. All errors should be handled. Reviewed-by:
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David Sterba authored
Function name in the comment does not bring much value to code not exposed as API and we don't stick to the kdoc format anymore. Update formatting of parameter descriptions. Reviewed-by:
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David Sterba authored
We keep the comments next to the implementation, there were some left to move. Reviewed-by:
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Anand Jain authored
Add a comment explaining the relationship between fsid and metadata_uuid in the on-disk superblock and the in-memory struct btrfs_fs_devices. Signed-off-by:
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Jiapeng Chong authored
These functions are defined in the qgroup.c file, but not called anymore since commit "btrfs: qgroup: use qgroup_iterator_nested to in qgroup_update_refcnt()" so we can delete them. fs/btrfs/qgroup.c:149:19: warning: unused function 'qgroup_to_aux'. fs/btrfs/qgroup.c:154:36: warning: unused function 'unode_aux_to_qgroup'. Reported-by:
Abaci Robot <abaci@linux.alibaba.com> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=6566Reviewed-by:
Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by:
Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Reviewed-by:
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Qu Wenruo authored
Currently we go GFP_ATOMIC allocation for qgroup relation add, this includes the following 3 call sites: - btrfs_read_qgroup_config() This is not really needed, as at that time we're still in single thread mode, and no spin lock is held. - btrfs_add_qgroup_relation() This one is holding a spinlock, but we're ensured to add at most one relation, thus we can easily do a preallocation and use the preallocated memory to avoid GFP_ATOMIC. - btrfs_qgroup_inherit() This is a little more tricky, as we may have as many relationships as inherit::num_qgroups. Thus we have to properly allocate an array then preallocate all the memory. This patch would remove the GFP_ATOMIC allocation for above involved call sites, by doing preallocation before holding the spinlock, and let __add_relation_rb() to handle the freeing of the structure. Signed-off-by:
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Qu Wenruo authored
Qgroup is the heaviest user of GFP_ATOMIC, but one call site does not really need GFP_ATOMIC, that is add_qgroup_rb(). That function only searches the rbtree to find if we already have such entry. If not, then it would try to allocate memory for it. This means we can afford to pre-allocate such structure unconditionally, then free the memory if it's not needed. Considering this function is not a hot path, only utilized by the following functions: - btrfs_qgroup_inherit() For "btrfs subvolume snapshot -i" option. - btrfs_read_qgroup_config() At mount time, and we're ensured there would be no existing rb tree entry for each qgroup. - btrfs_create_qgroup() Thus we're completely safe to pre-allocate the extra memory for btrfs_qgroup structure, and reduce unnecessary GFP_ATOMIC usage. Reviewed-by:
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Qu Wenruo authored
The ulist @qgroups is utilized to record all involved qgroups from both old and new roots inside btrfs_qgroup_account_extent(). Due to the fact that qgroup_update_refcnt() itself is already utilizing qgroup_iterator, here we have to introduce another list_head, btrfs_qgroup::nested_iterator, allowing nested iteration. Signed-off-by:
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