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The only time we actually leave the path spinning is if we're truncating a small amount and don't actually free an extent, which is not a common occurrence. We have to set the path blocking in order to add the delayed ref anyway, so the first extent we find we set the path to blocking and stay blocking for the duration of the operation. With the upcoming file extent map stuff there will be another case that we have to have the path blocking, so just swap to blocking always. Note: this patch also fixes a warning after28553fa992("Btrfs: fix race between shrinking truncate and fiemap") got merged that inserts extent locks around truncation so the path must not leave spinning locks after btrfs_search_slot. [70.794783] BUG: sleeping function called from invalid context at mm/slab.h:565 [70.794834] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1141, name: rsync [70.794863] 5 locks held by rsync/1141: [70.794876] #0: ffff888417b9c408 (sb_writers#17){.+.+}, at: mnt_want_write+0x20/0x50 [70.795030] #1: ffff888428de28e8 (&type->i_mutex_dir_key#13/1){+.+.}, at: lock_rename+0xf1/0x100 [70.795051] #2: ffff888417b9c608 (sb_internal#2){.+.+}, at: start_transaction+0x394/0x560 [70.795124] #3: ffff888403081768 (btrfs-fs-01){++++}, at: btrfs_try_tree_write_lock+0x2f/0x160 [70.795203] #4: ffff888403086568 (btrfs-fs-00){++++}, at: btrfs_try_tree_write_lock+0x2f/0x160 [70.795222] CPU: 5 PID: 1141 Comm: rsync Not tainted 5.6.0-rc2-backup+ #2 [70.795362] Call Trace: [70.795374] dump_stack+0x71/0xa0 [70.795445] ___might_sleep.part.96.cold.106+0xa6/0xb6 [70.795459] kmem_cache_alloc+0x1d3/0x290 [70.795471] alloc_extent_state+0x22/0x1c0 [70.795544] __clear_extent_bit+0x3ba/0x580 [70.795557] ? _raw_spin_unlock_irq+0x24/0x30 [70.795569] btrfs_truncate_inode_items+0x339/0xe50 [70.795647] btrfs_evict_inode+0x269/0x540 [70.795659] ? dput.part.38+0x29/0x460 [70.795671] evict+0xcd/0x190 [70.795682] __dentry_kill+0xd6/0x180 [70.795754] dput.part.38+0x2ad/0x460 [70.795765] do_renameat2+0x3cb/0x540 [70.795777] __x64_sys_rename+0x1c/0x20 Reported-by: Dave Jones <davej@codemonkey.org.uk> Fixes:28553fa992("Btrfs: fix race between shrinking truncate and fiemap") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ add note ] Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.