summaryrefslogtreecommitdiff
path: root/fs/9p/vfs_inode_dotl.c
diff options
context:
space:
mode:
authorHou Tao <houtao1@huawei.com>2019-01-24 14:35:13 +0800
committerDominique Martinet <dominique.martinet@cea.fr>2019-03-03 14:04:07 +0900
commit5e3cc1ee1405a7eb3487ed24f786dec01b4cbe1f (patch)
treed5bdf35b4c6bce3b46aed9b7d49cf28fed993682 /fs/9p/vfs_inode_dotl.c
parent3bbe8b1a4ae9585e9cf15e7036bf9e5374a482df (diff)
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/vfs_inode_dotl.c')
-rw-r--r--fs/9p/vfs_inode_dotl.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 4823e1c46999..a950a927a626 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -143,7 +143,7 @@ static struct inode *v9fs_qid_iget_dotl(struct super_block *sb,
if (retval)
goto error;
- v9fs_stat2inode_dotl(st, inode);
+ v9fs_stat2inode_dotl(st, inode, 0);
v9fs_cache_inode_get_cookie(inode);
retval = v9fs_get_acl(inode, fid);
if (retval)
@@ -496,7 +496,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
if (IS_ERR(st))
return PTR_ERR(st);
- v9fs_stat2inode_dotl(st, d_inode(dentry));
+ v9fs_stat2inode_dotl(st, d_inode(dentry), 0);
generic_fillattr(d_inode(dentry), stat);
/* Change block size to what the server returned */
stat->blksize = st->st_blksize;
@@ -607,11 +607,13 @@ int v9fs_vfs_setattr_dotl(struct dentry *dentry, struct iattr *iattr)
* v9fs_stat2inode_dotl - populate an inode structure with stat info
* @stat: stat structure
* @inode: inode to populate
+ * @flags: ctrl flags (e.g. V9FS_STAT2INODE_KEEP_ISIZE)
*
*/
void
-v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
+v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode,
+ unsigned int flags)
{
umode_t mode;
struct v9fs_inode *v9inode = V9FS_I(inode);
@@ -631,7 +633,8 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
mode |= inode->i_mode & ~S_IALLUGO;
inode->i_mode = mode;
- i_size_write(inode, stat->st_size);
+ if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE))
+ v9fs_i_size_write(inode, stat->st_size);
inode->i_blocks = stat->st_blocks;
} else {
if (stat->st_result_mask & P9_STATS_ATIME) {
@@ -661,8 +664,9 @@ v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
}
if (stat->st_result_mask & P9_STATS_RDEV)
inode->i_rdev = new_decode_dev(stat->st_rdev);
- if (stat->st_result_mask & P9_STATS_SIZE)
- i_size_write(inode, stat->st_size);
+ if (!(flags & V9FS_STAT2INODE_KEEP_ISIZE) &&
+ stat->st_result_mask & P9_STATS_SIZE)
+ v9fs_i_size_write(inode, stat->st_size);
if (stat->st_result_mask & P9_STATS_BLOCKS)
inode->i_blocks = stat->st_blocks;
}
@@ -928,9 +932,9 @@ v9fs_vfs_get_link_dotl(struct dentry *dentry,
int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
{
- loff_t i_size;
struct p9_stat_dotl *st;
struct v9fs_session_info *v9ses;
+ unsigned int flags;
v9ses = v9fs_inode2v9ses(inode);
st = p9_client_getattr_dotl(fid, P9_STATS_ALL);
@@ -942,16 +946,13 @@ int v9fs_refresh_inode_dotl(struct p9_fid *fid, struct inode *inode)
if ((inode->i_mode & S_IFMT) != (st->st_mode & S_IFMT))
goto out;
- spin_lock(&inode->i_lock);
/*
* We don't want to refresh inode->i_size,
* because we may have cached data
*/
- i_size = inode->i_size;
- v9fs_stat2inode_dotl(st, inode);
- if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
- inode->i_size = i_size;
- spin_unlock(&inode->i_lock);
+ flags = (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) ?
+ V9FS_STAT2INODE_KEEP_ISIZE : 0;
+ v9fs_stat2inode_dotl(st, inode, flags);
out:
kfree(st);
return 0;