Simplify and document OpenZFS library dependencies #1
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For those not already familiar with the code base it can be a challenge to understand how the libraries are laid out. This has sometimes resulted in functionality being added in the wrong place. To help avoid that in the future this commit documents the high-level dependencies for easy reference in lib/Makefile.am. It also simplifies a few things. - Switched libzpool dependency on libzfs_core to libzutil. This change makes it clear libzpool should never depend on the ioctl() functionality provided by libzfs_core. - Moved zfs_ioctl_fd() from libzutil to libzfs_core and renamed it lzc_ioctl_fd(). Normal access to the kmods should all be funneled through the libzfs_core library. The sole exception is the pool_active() which was updated to not use lzc_ioctl_fd() to remove the libzfs_core dependency. - Removed libzfs_core dependency on libzutil. - Removed the lib/libzfs/os/freebsd/libzfs_ioctl_compat.c source file which was all dead code. - Removed libzfs_core dependency from mkbusy and ctime test utilities. It was only needed for some trivial wrapper functions and that code is easy to replicate to shed the unneeded dependency. Reviewed-by: Ryan Moeller <ryan@ixsystems.com> Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Don Brady <don.brady@delphix.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes openzfs#12602
sundengyu
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Before this patch, in zfs_domount, if zfs_root or d_make_root fails, we leave zfsvfs != NULL. This will lead to execution of the error handling `if` statement at the `out` label, and hence to a call to dmu_objset_disown and zfsvfs_free. However, zfs_umount, which we call upon failure of zfs_root and d_make_root already does dmu_objset_disown and zfsvfs_free. I suppose this patch rather adds to the brittleness of this part of the code base, but I don't want to invest more time in this right now. To add a regression test, we'd need some kind of fault injection facility for zfs_root or d_make_root, which doesn't exist right now. And even then, I think that regression test would be too closely tied to the implementation. To repro the double-disown / double-free, do the following: 1. patch zfs_root to always return an error 2. mount a ZFS filesystem Here's the stack trace you would see then: VERIFY3(ds->ds_owner == tag) failed (0000000000000000 == ffff9142361e8000) PANIC at dsl_dataset.c:1003:dsl_dataset_disown() Showing stack for process 28332 CPU: 2 PID: 28332 Comm: zpool Tainted: G O 5.10.103-1.nutanix.el7.x86_64 #1 Call Trace: dump_stack+0x74/0x92 spl_dumpstack+0x29/0x2b [spl] spl_panic+0xd4/0xfc [spl] dsl_dataset_disown+0xe9/0x150 [zfs] dmu_objset_disown+0xd6/0x150 [zfs] zfs_domount+0x17b/0x4b0 [zfs] zpl_mount+0x174/0x220 [zfs] legacy_get_tree+0x2b/0x50 vfs_get_tree+0x2a/0xc0 path_mount+0x2fa/0xa70 do_mount+0x7c/0xa0 __x64_sys_mount+0x8b/0xe0 do_syscall_64+0x38/0x50 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ryan Moeller <ryan@iXsystems.com> Co-authored-by: Christian Schwarz <christian.schwarz@nutanix.com> Signed-off-by: Christian Schwarz <christian.schwarz@nutanix.com> Closes openzfs#14025
sundengyu
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Under certain loads, the following panic is hit:
panic: page fault
KDB: stack backtrace:
#0 0xffffffff805db025 at kdb_backtrace+0x65
#1 0xffffffff8058e86f at vpanic+0x17f
#2 0xffffffff8058e6e3 at panic+0x43
#3 0xffffffff808adc15 at trap_fatal+0x385
#4 0xffffffff808adc6f at trap_pfault+0x4f
#5 0xffffffff80886da8 at calltrap+0x8
#6 0xffffffff80669186 at vgonel+0x186
#7 0xffffffff80669841 at vgone+0x31
#8 0xffffffff8065806d at vfs_hash_insert+0x26d
#9 0xffffffff81a39069 at sfs_vgetx+0x149
#10 0xffffffff81a39c54 at zfsctl_snapdir_lookup+0x1e4
#11 0xffffffff8065a28c at lookup+0x45c
#12 0xffffffff806594b9 at namei+0x259
#13 0xffffffff80676a33 at kern_statat+0xf3
#14 0xffffffff8067712f at sys_fstatat+0x2f
#15 0xffffffff808ae50c at amd64_syscall+0x10c
#16 0xffffffff808876bb at fast_syscall_common+0xf8
The page fault occurs because vgonel() will call VOP_CLOSE() for active
vnodes. For this reason, define vop_close for zfsctl_ops_snapshot. While
here, define vop_open for consistency.
After adding the necessary vop, the bug progresses to the following
panic:
panic: VERIFY3(vrecycle(vp) == 1) failed (0 == 1)
cpuid = 17
KDB: stack backtrace:
#0 0xffffffff805e29c5 at kdb_backtrace+0x65
#1 0xffffffff8059620f at vpanic+0x17f
#2 0xffffffff81a27f4a at spl_panic+0x3a
#3 0xffffffff81a3a4d0 at zfsctl_snapshot_inactive+0x40
#4 0xffffffff8066fdee at vinactivef+0xde
#5 0xffffffff80670b8a at vgonel+0x1ea
#6 0xffffffff806711e1 at vgone+0x31
#7 0xffffffff8065fa0d at vfs_hash_insert+0x26d
#8 0xffffffff81a39069 at sfs_vgetx+0x149
#9 0xffffffff81a39c54 at zfsctl_snapdir_lookup+0x1e4
#10 0xffffffff80661c2c at lookup+0x45c
#11 0xffffffff80660e59 at namei+0x259
#12 0xffffffff8067e3d3 at kern_statat+0xf3
#13 0xffffffff8067eacf at sys_fstatat+0x2f
#14 0xffffffff808b5ecc at amd64_syscall+0x10c
#15 0xffffffff8088f07b at fast_syscall_common+0xf8
This is caused by a race condition that can occur when allocating a new
vnode and adding that vnode to the vfs hash. If the newly created vnode
loses the race when being inserted into the vfs hash, it will not be
recycled as its usecount is greater than zero, hitting the above
assertion.
Fix this by dropping the assertion.
FreeBSD-issue: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=252700
Reviewed-by: Andriy Gapon <avg@FreeBSD.org>
Reviewed-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Alek Pinchuk <apinchuk@axcient.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Rob Wing <rob.wing@klarasystems.com>
Co-authored-by: Rob Wing <rob.wing@klarasystems.com>
Submitted-by: Klara, Inc.
Sponsored-by: rsync.net
Closes openzfs#14501
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For those not already familiar with the code base it can be a
challenge to understand how the libraries are laid out. This
has sometimes resulted in functionality being added in the
wrong place. To help avoid that in the future this commit
documents the high-level dependencies for easy reference in
lib/Makefile.am. It also simplifies a few things.
Switched libzpool dependency on libzfs_core to libzutil.
This change makes it clear libzpool should never depend
on the ioctl() functionality provided by libzfs_core.
Moved zfs_ioctl_fd() from libzutil to libzfs_core and
renamed it lzc_ioctl_fd(). Normal access to the kmods
should all be funneled through the libzfs_core library.
The sole exception is the pool_active() which was updated
to not use lzc_ioctl_fd() to remove the libzfs_core
dependency.
Removed libzfs_core dependency on libzutil.
Removed the lib/libzfs/os/freebsd/libzfs_ioctl_compat.c
source file which was all dead code.
Removed libzfs_core dependency from mkbusy and ctime
test utilities. It was only needed for some trivial
wrapper functions and that code is easy to replicate
to shed the unneeded dependency.
Reviewed-by: Ryan Moeller ryan@ixsystems.com
Reviewed-by: Tony Hutter hutter2@llnl.gov
Reviewed-by: Don Brady don.brady@delphix.com
Signed-off-by: Brian Behlendorf behlendorf1@llnl.gov
Closes openzfs#12602
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