diff options
author | Hou Tao <houtao1@huawei.com> | 2019-01-24 14:35:13 +0800 |
---|---|---|
committer | Dominique Martinet <dominique.martinet@cea.fr> | 2019-03-03 14:04:07 +0900 |
commit | 5e3cc1ee1405a7eb3487ed24f786dec01b4cbe1f (patch) | |
tree | d5bdf35b4c6bce3b46aed9b7d49cf28fed993682 /fs/9p/v9fs_vfs.h | |
parent | 3bbe8b1a4ae9585e9cf15e7036bf9e5374a482df (diff) | |
download | linux-5e3cc1ee1405a7eb3487ed24f786dec01b4cbe1f.tar.bz2 |
9p: use inode->i_lock to protect i_size_write() under 32-bit
Use inode->i_lock to protect i_size_write(), else i_size_read() in
generic_fillattr() may loop infinitely in read_seqcount_begin() when
multiple processes invoke v9fs_vfs_getattr() or v9fs_vfs_getattr_dotl()
simultaneously under 32-bit SMP environment, and a soft lockup will be
triggered as show below:
watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [stat:2217]
Modules linked in:
CPU: 5 PID: 2217 Comm: stat Not tainted 5.0.0-rc1-00005-g7f702faf5a9e #4
Hardware name: Generic DT based system
PC is at generic_fillattr+0x104/0x108
LR is at 0xec497f00
pc : [<802b8898>] lr : [<ec497f00>] psr: 200c0013
sp : ec497e20 ip : ed608030 fp : ec497e3c
r10: 00000000 r9 : ec497f00 r8 : ed608030
r7 : ec497ebc r6 : ec497f00 r5 : ee5c1550 r4 : ee005780
r3 : 0000052d r2 : 00000000 r1 : ec497f00 r0 : ed608030
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: ac48006a DAC: 00000051
CPU: 5 PID: 2217 Comm: stat Not tainted 5.0.0-rc1-00005-g7f702faf5a9e #4
Hardware name: Generic DT based system
Backtrace:
[<8010d974>] (dump_backtrace) from [<8010dc88>] (show_stack+0x20/0x24)
[<8010dc68>] (show_stack) from [<80a1d194>] (dump_stack+0xb0/0xdc)
[<80a1d0e4>] (dump_stack) from [<80109f34>] (show_regs+0x1c/0x20)
[<80109f18>] (show_regs) from [<801d0a80>] (watchdog_timer_fn+0x280/0x2f8)
[<801d0800>] (watchdog_timer_fn) from [<80198658>] (__hrtimer_run_queues+0x18c/0x380)
[<801984cc>] (__hrtimer_run_queues) from [<80198e60>] (hrtimer_run_queues+0xb8/0xf0)
[<80198da8>] (hrtimer_run_queues) from [<801973e8>] (run_local_timers+0x28/0x64)
[<801973c0>] (run_local_timers) from [<80197460>] (update_process_times+0x3c/0x6c)
[<80197424>] (update_process_times) from [<801ab2b8>] (tick_nohz_handler+0xe0/0x1bc)
[<801ab1d8>] (tick_nohz_handler) from [<80843050>] (arch_timer_handler_virt+0x38/0x48)
[<80843018>] (arch_timer_handler_virt) from [<80180a64>] (handle_percpu_devid_irq+0x8c/0x240)
[<801809d8>] (handle_percpu_devid_irq) from [<8017ac20>] (generic_handle_irq+0x34/0x44)
[<8017abec>] (generic_handle_irq) from [<8017b344>] (__handle_domain_irq+0x6c/0xc4)
[<8017b2d8>] (__handle_domain_irq) from [<801022e0>] (gic_handle_irq+0x4c/0x88)
[<80102294>] (gic_handle_irq) from [<80101a30>] (__irq_svc+0x70/0x98)
[<802b8794>] (generic_fillattr) from [<8056b284>] (v9fs_vfs_getattr_dotl+0x74/0xa4)
[<8056b210>] (v9fs_vfs_getattr_dotl) from [<802b8904>] (vfs_getattr_nosec+0x68/0x7c)
[<802b889c>] (vfs_getattr_nosec) from [<802b895c>] (vfs_getattr+0x44/0x48)
[<802b8918>] (vfs_getattr) from [<802b8a74>] (vfs_statx+0x9c/0xec)
[<802b89d8>] (vfs_statx) from [<802b9428>] (sys_lstat64+0x48/0x78)
[<802b93e0>] (sys_lstat64) from [<80101000>] (ret_fast_syscall+0x0/0x28)
[dominique.martinet@cea.fr: updated comment to not refer to a function
in another subsystem]
Link: http://lkml.kernel.org/r/20190124063514.8571-2-houtao1@huawei.com
Cc: stable@vger.kernel.org
Fixes: 7549ae3e81cc ("9p: Use the i_size_[read, write]() macros instead of using inode->i_size directly.")
Reported-by: Xing Gaopeng <xingaopeng@huawei.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Diffstat (limited to 'fs/9p/v9fs_vfs.h')
-rw-r--r-- | fs/9p/v9fs_vfs.h | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/fs/9p/v9fs_vfs.h b/fs/9p/v9fs_vfs.h index 5a0db6dec8d1..aaee1e6584e6 100644 --- a/fs/9p/v9fs_vfs.h +++ b/fs/9p/v9fs_vfs.h @@ -40,6 +40,9 @@ */ #define P9_LOCK_TIMEOUT (30*HZ) +/* flags for v9fs_stat2inode() & v9fs_stat2inode_dotl() */ +#define V9FS_STAT2INODE_KEEP_ISIZE 1 + extern struct file_system_type v9fs_fs_type; extern const struct address_space_operations v9fs_addr_operations; extern const struct file_operations v9fs_file_operations; @@ -61,8 +64,10 @@ int v9fs_init_inode(struct v9fs_session_info *v9ses, struct inode *inode, umode_t mode, dev_t); void v9fs_evict_inode(struct inode *inode); ino_t v9fs_qid2ino(struct p9_qid *qid); -void v9fs_stat2inode(struct p9_wstat *, struct inode *, struct super_block *); -void v9fs_stat2inode_dotl(struct p9_stat_dotl *, struct inode *); +void v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode, + struct super_block *sb, unsigned int flags); +void v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode, + unsigned int flags); int v9fs_dir_release(struct inode *inode, struct file *filp); int v9fs_file_open(struct inode *inode, struct file *file); void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat); @@ -83,4 +88,18 @@ static inline void v9fs_invalidate_inode_attr(struct inode *inode) } int v9fs_open_to_dotl_flags(int flags); + +static inline void v9fs_i_size_write(struct inode *inode, loff_t i_size) +{ + /* + * 32-bit need the lock, concurrent updates could break the + * sequences and make i_size_read() loop forever. + * 64-bit updates are atomic and can skip the locking. + */ + if (sizeof(i_size) > sizeof(long)) + spin_lock(&inode->i_lock); + i_size_write(inode, i_size); + if (sizeof(i_size) > sizeof(long)) + spin_unlock(&inode->i_lock); +} #endif |