- 23 Aug, 2021 40 commits
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Christian Brauner authored
Enable btrfs_setattr() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by:
David Sterba <dsterba@suse.com> Signed-off-by:
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Christian Brauner authored
Enable btrfs_tmpfile() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_symlink() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_mkdir() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_create() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_mknod() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_getattr() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Enable btrfs_rename() to handle idmapped mounts. This is just a matter of passing down the mount's userns. Reviewed-by:
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Christian Brauner authored
Extend btrfs_new_inode() to take the idmapped mount into account when initializing a new inode. This is just a matter of passing down the mount's userns. The rest is taken care of in inode_init_owner(). This is a preliminary patch to make the individual btrfs inode operations idmapped mount aware. Reviewed-by:
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Christian Brauner authored
Various filesystems rely on the lookup_one_len() helper to lookup a single path component relative to a well-known starting point. Allow such filesystems to support idmapped mounts by adding a version of this helper to take the idmap into account when calling inode_permission(). This change is a required to let btrfs (and other filesystems) support idmapped mounts. Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: linux-fsdevel@vger.kernel.org Reviewed-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Anand Jain authored
Sysfs file has grown big. It takes some time to locate the correct struct attribute to add new files. Create a table and map the struct attribute to its sysfs path. Also, fix the comment about the debug sysfs path. And add the comments to the attributes instead of attribute group, where sysfs file names are defined. Signed-off-by:
Anand Jain <anand.jain@oracle.com> Reviewed-by:
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Qu Wenruo authored
[BUG] It's easy to trigger NULL pointer dereference, just by removing a non-existing device id: # mkfs.btrfs -f -m single -d single /dev/test/scratch1 \ /dev/test/scratch2 # mount /dev/test/scratch1 /mnt/btrfs # btrfs device remove 3 /mnt/btrfs Then we have the following kernel NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 9 PID: 649 Comm: btrfs Not tainted 5.14.0-rc3-custom+ #35 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:btrfs_rm_device+0x4de/0x6b0 [btrfs] btrfs_ioctl+0x18bb/0x3190 [btrfs] ? lock_is_held_type+0xa5/0x120 ? find_held_lock.constprop.0+0x2b/0x80 ? do_user_addr_fault+0x201/0x6a0 ? lock_release+0xd2/0x2d0 ? __x64_sys_ioctl+0x83/0xb0 __x64_sys_ioctl+0x83/0xb0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae [CAUSE] Commit a27a94c2 ("btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly") moves the "missing" device path check into btrfs_rm_device(). But btrfs_rm_device() itself can have case where it only receives @devid, with NULL as @device_path. In that case, calling strcmp() on NULL will trigger the NULL pointer dereference. Before that commit, we handle the "missing" case inside btrfs_find_device_by_devspec(), which will not check @device_path at all if @devid is provided, thus no way to trigger the bug. [FIX] Before calling strcmp(), also make sure @device_path is not NULL. Fixes: a27a94c2 ("btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly") CC: stable@vger.kernel.org # 5.4+ Reported-by:
butt3rflyh4ck <butterflyhuangxx@gmail.com> Reviewed-by:
Qu Wenruo <wqu@suse.com> Reviewed-by:
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Naohiro Aota authored
We call split_zoned_em() on an extent_map on submitting a bio for it. Thus, we can assume the extent_map is PINNED, not LOGGING, and in the modified list. Add ASSERT()s to ensure the extent_maps after the split also has the proper flags set and are in the modified list. Suggested-by:
Filipe Manana <fdmanana@suse.com> Reviewed-by:
Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by:
Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by:
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Naohiro Aota authored
alloc_offset is offset from the start of a block group and @offset is actually an address in logical space. Thus, we need to consider block_group->start when calculating them. Fixes: 011b41bf ("btrfs: zoned: advance allocation pointer after tree log node") CC: stable@vger.kernel.org # 5.12+ Signed-off-by:
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Naohiro Aota authored
btrfs_relocate_chunk() can fail with -EAGAIN when e.g. send operations are running. The message can fail btrfs/187 and it's unnecessary because we anyway add it back to the reclaim list. btrfs_reclaim_bgs_work() `-> btrfs_relocate_chunk() `-> btrfs_relocate_block_group() `-> reloc_chunk_start() `-> if (fs_info->send_in_progress) `-> return -EAGAIN CC: stable@vger.kernel.org # 5.13+ Fixes: 18bb8bbf ("btrfs: zoned: automatically reclaim zones") Reviewed-by: -
Johannes Thumshirn authored
Automatically reclaiming dirty zones might not always be desired for all workloads, especially as there are currently still some rough edges with the relocation code on zoned filesystems. Allow disabling zone auto reclaim on a per filesystem basis by writing 0 as the threshold value. Reviewed-by:
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Filipe Manana authored
A comment at log_conflicting_inodes() mentions that we check the inode's logged_trans field instead of using btrfs_inode_in_log() because the field last_log_commit is not updated when we log that an inode exists and the inode has the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) set. The part about the full sync flag is not true anymore since commit 9acc8103 ("btrfs: fix unpersisted i_size on fsync after expanding truncate"), so update the comment to not mention that part anymore. Signed-off-by:
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Filipe Manana authored
Now that we are checking if the inode's logged_trans is 0 to detect the possibility of the inode having been evicted and reloaded, the test for the full sync flag (BTRFS_INODE_NEEDS_FULL_SYNC) is no longer needed at tree-log.c:inode_logged(). Its purpose was to detect the possibility of a previous eviction as well, since when an inode is loaded the full sync flag is always set on it (and only cleared after the inode is logged). So just remove the check and update the comment. The check for the inode's logged_trans being 0 was added recently by the patch with the subject "btrfs: eliminate some false positives when checking if inode was logged". Signed-off-by:
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Filipe Manana authored
At the very end of btrfs_rename_exchange(), in case an error happened, we are checking if 'new_inode' is NULL, but that is not needed since during a rename exchange, unlike regular renames, 'new_inode' can never be NULL, and if it were, we would have a crashed much earlier when we dereference it multiple times. So remove the check because it is not necessary and because it is causing static checkers to emit a warning. I probably introduced the check by copy-pasting similar code from btrfs_rename(), where 'new_inode' can be NULL, in commit 86e8aa0e ("Btrfs: unpin logs if rename exchange operation fails"). Reported-by:
kernel test robot <lkp@intel.com> Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
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Goldwyn Rodrigues authored
Instead of using kmalloc() to allocate backref_ctx, allocate backref_ctx on stack. The size is reasonably small. sizeof(backref_ctx) = 48 Reviewed-by:
Goldwyn Rodrigues <rgoldwyn@suse.com> Signed-off-by:
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Goldwyn Rodrigues authored
Instead of using kmalloc() to allocate btrfs_ioctl_defrag_range_args, allocate btrfs_ioctl_defrag_range_args on stack, the size is reasonably small and ioctls are called in process context. sizeof(btrfs_ioctl_defrag_range_args) = 48 Reviewed-by:
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Goldwyn Rodrigues authored
Instead of using kmalloc() to allocate btrfs_ioctl_quota_rescan_args, allocate btrfs_ioctl_quota_rescan_args on stack, the size is reasonably small and ioctls are called in process context. sizeof(btrfs_ioctl_quota_rescan_args) = 64 Reviewed-by:
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Goldwyn Rodrigues authored
Instead of allocating file_ra_state using kmalloc, allocate on stack. sizeof(struct readahead) = 32 bytes. Reviewed-by:
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Marcos Paulo de Souza authored
It's a common practice to start a search using offset (u64)-1, which is the u64 maximum value, meaning that we want the search_slot function to be set in the last item with the same objectid and type. Once we are in this position, it's a matter to start a search backwards by calling btrfs_previous_item, which will check if we'll need to go to a previous leaf and other necessary checks, only to be sure that we are in last offset of the same object and type. The new btrfs_search_backwards function does the all these steps when necessary, and can be used to avoid code duplication. Signed-off-by:
Marcos Paulo de Souza <mpdesouza@suse.com> Reviewed-by:
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David Sterba authored
As fsverity support depends on a config option, print that at module load time like we do for similar features. Reviewed-by:
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Boris Burkov authored
Writing out the verity data is too large of an operation to do in a single transaction. If we are interrupted before we finish creating fsverity metadata for a file, or fail to clean up already created metadata after a failure, we could leak the verity items that we already committed. To address this issue, we use the orphan mechanism. When we start enabling verity on a file, we also add an orphan item for that inode. When we are finished, we delete the orphan. However, if we are interrupted midway, the orphan will be present at mount and we can cleanup the half-formed verity state. There is a possible race with a normal unlink operation: if unlink and verity run on the same file in parallel, it is possible for verity to succeed and delete the still legitimate orphan added by unlink. Then, if we are interrupted and mount in that state, we will never clean up the inode properly. This is also possible for a file created with O_TMPFILE. Check nlink==0 before deleting to avoid this race. A final thing to note is that this is a resurrection of using orphans to signal an operation besides "delete this inode". The old case was to signal the need to do a truncate. That case still technically applies for mounting very old file systems, so we need to take some care to not clobber it. To that end, we just have to be careful that verity orphan cleanup is a no-op for non-verity files. Signed-off-by:
Boris Burkov <boris@bur.io> Reviewed-by:
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Boris Burkov authored
Add support for fsverity in btrfs. To support the generic interface in fs/verity, we add two new item types in the fs tree for inodes with verity enabled. One stores the per-file verity descriptor and btrfs verity item and the other stores the Merkle tree data itself. Verity checking is done in end_page_read just before a page is marked uptodate. This naturally handles a variety of edge cases like holes, preallocated extents, and inline extents. Some care needs to be taken to not try to verity pages past the end of the file, which are accessed by the generic buffered file reading code under some circumstances like reading to the end of the last page and trying to read again. Direct IO on a verity file falls back to buffered reads. Verity relies on PageChecked for the Merkle tree data itself to avoid re-walking up shared paths in the tree. For this reason, we need to cache the Merkle tree data. Since the file is immutable after verity is turned on, we can cache it at an index past EOF. Use the new inode ro_flags to store verity on the inode item, so that we can enable verity on a file, then rollback to an older kernel and still mount the file system and read the file. Since we can't safely write the file anymore without ruining the invariants of the Merkle tree, we mark a ro_compat flag on the file system when a file has verity enabled. Acked-by:
Eric Biggers <ebiggers@google.com> Co-developed-by:
Chris Mason <clm@fb.com> Signed-off-by:
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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:
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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:
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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:
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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:
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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:
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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:
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:
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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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