From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- fs/ceph/io.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 213 insertions(+) create mode 100644 fs/ceph/io.c (limited to 'fs/ceph/io.c') diff --git a/fs/ceph/io.c b/fs/ceph/io.c new file mode 100644 index 000000000..2d10f49c9 --- /dev/null +++ b/fs/ceph/io.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2016 Trond Myklebust + * Copyright (c) 2019 Jeff Layton + * + * I/O and data path helper functionality. + * + * Heavily borrowed from equivalent code in fs/nfs/io.c + */ + +#include + +#include +#include +#include +#include + +#include "super.h" +#include "io.h" + +/* Call with exclusively locked inode->i_rwsem */ +static void ceph_block_o_direct(struct ceph_inode_info *ci, struct inode *inode) +{ + bool is_odirect; + + lockdep_assert_held_write(&inode->i_rwsem); + + spin_lock(&ci->i_ceph_lock); + /* ensure that bit state is consistent */ + smp_mb__before_atomic(); + is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT; + if (is_odirect) { + clear_bit(CEPH_I_ODIRECT_BIT, &ci->i_ceph_flags); + /* ensure modified bit is visible */ + smp_mb__after_atomic(); + } + spin_unlock(&ci->i_ceph_lock); + + if (is_odirect) + inode_dio_wait(inode); +} + +/** + * ceph_start_io_read - declare the file is being used for buffered reads + * @inode: file inode + * + * Declare that a buffered read operation is about to start, and ensure + * that we block all direct I/O. + * On exit, the function ensures that the CEPH_I_ODIRECT flag is unset, + * and holds a shared lock on inode->i_rwsem to ensure that the flag + * cannot be changed. + * In practice, this means that buffered read operations are allowed to + * execute in parallel, thanks to the shared lock, whereas direct I/O + * operations need to wait to grab an exclusive lock in order to set + * CEPH_I_ODIRECT. + * Note that buffered writes and truncates both take a write lock on + * inode->i_rwsem, meaning that those are serialised w.r.t. the reads. + */ +int ceph_start_io_read(struct inode *inode) +{ + struct ceph_inode_info *ci = ceph_inode(inode); + bool is_odirect; + int err; + + /* Be an optimist! */ + err = down_read_killable(&inode->i_rwsem); + if (err) + return err; + + spin_lock(&ci->i_ceph_lock); + /* ensure that bit state is consistent */ + smp_mb__before_atomic(); + is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT; + spin_unlock(&ci->i_ceph_lock); + if (!is_odirect) + return 0; + up_read(&inode->i_rwsem); + + /* Slow path.... */ + err = down_write_killable(&inode->i_rwsem); + if (err) + return err; + + ceph_block_o_direct(ci, inode); + downgrade_write(&inode->i_rwsem); + + return 0; +} + +/** + * ceph_end_io_read - declare that the buffered read operation is done + * @inode: file inode + * + * Declare that a buffered read operation is done, and release the shared + * lock on inode->i_rwsem. + */ +void +ceph_end_io_read(struct inode *inode) +{ + up_read(&inode->i_rwsem); +} + +/** + * ceph_start_io_write - declare the file is being used for buffered writes + * @inode: file inode + * + * Declare that a buffered write operation is about to start, and ensure + * that we block all direct I/O. + */ +int ceph_start_io_write(struct inode *inode) +{ + int err = down_write_killable(&inode->i_rwsem); + if (!err) + ceph_block_o_direct(ceph_inode(inode), inode); + return err; +} + +/** + * ceph_end_io_write - declare that the buffered write operation is done + * @inode: file inode + * + * Declare that a buffered write operation is done, and release the + * lock on inode->i_rwsem. + */ +void +ceph_end_io_write(struct inode *inode) +{ + up_write(&inode->i_rwsem); +} + +/* Call with exclusively locked inode->i_rwsem */ +static void ceph_block_buffered(struct ceph_inode_info *ci, struct inode *inode) +{ + bool is_odirect; + + lockdep_assert_held_write(&inode->i_rwsem); + + spin_lock(&ci->i_ceph_lock); + /* ensure that bit state is consistent */ + smp_mb__before_atomic(); + is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT; + if (!is_odirect) { + set_bit(CEPH_I_ODIRECT_BIT, &ci->i_ceph_flags); + /* ensure modified bit is visible */ + smp_mb__after_atomic(); + } + spin_unlock(&ci->i_ceph_lock); + + if (!is_odirect) { + /* FIXME: unmap_mapping_range? */ + filemap_write_and_wait(inode->i_mapping); + } +} + +/** + * ceph_start_io_direct - declare the file is being used for direct i/o + * @inode: file inode + * + * Declare that a direct I/O operation is about to start, and ensure + * that we block all buffered I/O. + * On exit, the function ensures that the CEPH_I_ODIRECT flag is set, + * and holds a shared lock on inode->i_rwsem to ensure that the flag + * cannot be changed. + * In practice, this means that direct I/O operations are allowed to + * execute in parallel, thanks to the shared lock, whereas buffered I/O + * operations need to wait to grab an exclusive lock in order to clear + * CEPH_I_ODIRECT. + * Note that buffered writes and truncates both take a write lock on + * inode->i_rwsem, meaning that those are serialised w.r.t. O_DIRECT. + */ +int ceph_start_io_direct(struct inode *inode) +{ + struct ceph_inode_info *ci = ceph_inode(inode); + bool is_odirect; + int err; + + /* Be an optimist! */ + err = down_read_killable(&inode->i_rwsem); + if (err) + return err; + + spin_lock(&ci->i_ceph_lock); + /* ensure that bit state is consistent */ + smp_mb__before_atomic(); + is_odirect = READ_ONCE(ci->i_ceph_flags) & CEPH_I_ODIRECT; + spin_unlock(&ci->i_ceph_lock); + if (is_odirect) + return 0; + up_read(&inode->i_rwsem); + + /* Slow path.... */ + err = down_write_killable(&inode->i_rwsem); + if (err) + return err; + + ceph_block_buffered(ci, inode); + downgrade_write(&inode->i_rwsem); + + return 0; +} + +/** + * ceph_end_io_direct - declare that the direct i/o operation is done + * @inode: file inode + * + * Declare that a direct I/O operation is done, and release the shared + * lock on inode->i_rwsem. + */ +void +ceph_end_io_direct(struct inode *inode) +{ + up_read(&inode->i_rwsem); +} -- cgit v1.3.1