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ceph: ceph_pagelist_append might sleep while atomic

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Ceph's encode_caps_cb() worked hard to not call __page_cache_alloc()
while holding a lock, but it's spoiled because ceph_pagelist_addpage()
always calls kmap(), which might sleep.  Here's the result:

[13439.295457] ceph: mds0 reconnect start
[13439.300572] BUG: sleeping function called from invalid context at include/linux/highmem.h:58
[13439.309243] in_atomic(): 1, irqs_disabled(): 0, pid: 12059, name: kworker/1:1
    . . .
[13439.376225] Call Trace:
[13439.378757]  [<ffffffff81076f4c>] __might_sleep+0xfc/0x110
[13439.384353]  [<ffffffffa03f4ce0>] ceph_pagelist_append+0x120/0x1b0 [libceph]
[13439.391491]  [<ffffffffa0448fe9>] ceph_encode_locks+0x89/0x190 [ceph]
[13439.398035]  [<ffffffff814ee849>] ? _raw_spin_lock+0x49/0x50
[13439.403775]  [<ffffffff811cadf5>] ? lock_flocks+0x15/0x20
[13439.409277]  [<ffffffffa045e2af>] encode_caps_cb+0x41f/0x4a0 [ceph]
[13439.415622]  [<ffffffff81196748>] ? igrab+0x28/0x70
[13439.420610]  [<ffffffffa045e9f8>] ? iterate_session_caps+0xe8/0x250 [ceph]
[13439.427584]  [<ffffffffa045ea25>] iterate_session_caps+0x115/0x250 [ceph]
[13439.434499]  [<ffffffffa045de90>] ? set_request_path_attr+0x2d0/0x2d0 [ceph]
[13439.441646]  [<ffffffffa0462888>] send_mds_reconnect+0x238/0x450 [ceph]
[13439.448363]  [<ffffffffa0464542>] ? ceph_mdsmap_decode+0x5e2/0x770 [ceph]
[13439.455250]  [<ffffffffa0462e42>] check_new_map+0x352/0x500 [ceph]
[13439.461534]  [<ffffffffa04631ad>] ceph_mdsc_handle_map+0x1bd/0x260 [ceph]
[13439.468432]  [<ffffffff814ebc7e>] ? mutex_unlock+0xe/0x10
[13439.473934]  [<ffffffffa043c612>] extra_mon_dispatch+0x22/0x30 [ceph]
[13439.480464]  [<ffffffffa03f6c2c>] dispatch+0xbc/0x110 [libceph]
[13439.486492]  [<ffffffffa03eec3d>] process_message+0x1ad/0x1d0 [libceph]
[13439.493190]  [<ffffffffa03f1498>] ? read_partial_message+0x3e8/0x520 [libceph]
    . . .
[13439.587132] ceph: mds0 reconnect success
[13490.720032] ceph: mds0 caps stale
[13501.235257] ceph: mds0 recovery completed
[13501.300419] ceph: mds0 caps renewed

Fix it up by encoding locks into a buffer first, and when the number
of encoded locks is stable, copy that into a ceph_pagelist.

[elder@inktank.com: abbreviated the stack info a bit.]

Cc: stable@vger.kernel.org # 3.4+
Signed-off-by: Jim Schutt <jaschut@sandia.gov>
Reviewed-by: Alex Elder <elder@inktank.com>
This commit is contained in:
Jim Schutt 2013-05-15 13:03:35 -05:00 committed by Alex Elder
parent c420276a53
commit 39be95e9c8
3 changed files with 88 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
fs/ceph/locks.c
View File

@ -191,29 +191,23 @@ void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
}
/**
* Encode the flock and fcntl locks for the given inode into the pagelist.
* Format is: #fcntl locks, sequential fcntl locks, #flock locks,
* sequential flock locks.
* Must be called with lock_flocks() already held.
* If we encounter more of a specific lock type than expected,
* we return the value 1.
* Encode the flock and fcntl locks for the given inode into the ceph_filelock
* array. Must be called with lock_flocks() already held.
* If we encounter more of a specific lock type than expected, return -ENOSPC.
*/
int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
int num_fcntl_locks, int num_flock_locks)
int ceph_encode_locks_to_buffer(struct inode *inode,
struct ceph_filelock *flocks,
int num_fcntl_locks, int num_flock_locks)
{
struct file_lock *lock;
struct ceph_filelock cephlock;
int err = 0;
int seen_fcntl = 0;
int seen_flock = 0;
__le32 nlocks;
int l = 0;
dout("encoding %d flock and %d fcntl locks", num_flock_locks,
num_fcntl_locks);
nlocks = cpu_to_le32(num_fcntl_locks);
err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
if (err)
goto fail;
for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
if (lock->fl_flags & FL_POSIX) {
++seen_fcntl;
@ -221,20 +215,12 @@ int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
err = -ENOSPC;
goto fail;
}
err = lock_to_ceph_filelock(lock, &cephlock);
err = lock_to_ceph_filelock(lock, &flocks[l]);
if (err)
goto fail;
err = ceph_pagelist_append(pagelist, &cephlock,
sizeof(struct ceph_filelock));
++l;
}
if (err)
goto fail;
}
nlocks = cpu_to_le32(num_flock_locks);
err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
if (err)
goto fail;
for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
if (lock->fl_flags & FL_FLOCK) {
++seen_flock;
@ -242,19 +228,51 @@ int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
err = -ENOSPC;
goto fail;
}
err = lock_to_ceph_filelock(lock, &cephlock);
err = lock_to_ceph_filelock(lock, &flocks[l]);
if (err)
goto fail;
err = ceph_pagelist_append(pagelist, &cephlock,
sizeof(struct ceph_filelock));
++l;
}
if (err)
goto fail;
}
fail:
return err;
}
/**
* Copy the encoded flock and fcntl locks into the pagelist.
* Format is: #fcntl locks, sequential fcntl locks, #flock locks,
* sequential flock locks.
* Returns zero on success.
*/
int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
struct ceph_pagelist *pagelist,
int num_fcntl_locks, int num_flock_locks)
{
int err = 0;
__le32 nlocks;
nlocks = cpu_to_le32(num_fcntl_locks);
err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
if (err)
goto out_fail;
err = ceph_pagelist_append(pagelist, flocks,
num_fcntl_locks * sizeof(*flocks));
if (err)
goto out_fail;
nlocks = cpu_to_le32(num_flock_locks);
err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
if (err)
goto out_fail;
err = ceph_pagelist_append(pagelist,
&flocks[num_fcntl_locks],
num_flock_locks * sizeof(*flocks));
out_fail:
return err;
}
/*
* Given a pointer to a lock, convert it to a ceph filelock
*/

63
fs/ceph/mds_client.c
View File

@ -2478,39 +2478,44 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
if (recon_state->flock) {
int num_fcntl_locks, num_flock_locks;
struct ceph_pagelist_cursor trunc_point;
struct ceph_filelock *flocks;
ceph_pagelist_set_cursor(pagelist, &trunc_point);
do {
lock_flocks();
ceph_count_locks(inode, &num_fcntl_locks,
&num_flock_locks);
rec.v2.flock_len = cpu_to_le32(2*sizeof(u32) +
(num_fcntl_locks+num_flock_locks) *
sizeof(struct ceph_filelock));
unlock_flocks();
/* pre-alloc pagelist */
ceph_pagelist_truncate(pagelist, &trunc_point);
err = ceph_pagelist_append(pagelist, &rec, reclen);
if (!err)
err = ceph_pagelist_reserve(pagelist,
rec.v2.flock_len);
/* encode locks */
if (!err) {
lock_flocks();
err = ceph_encode_locks(inode,
pagelist,
num_fcntl_locks,
num_flock_locks);
unlock_flocks();
}
} while (err == -ENOSPC);
encode_again:
lock_flocks();
ceph_count_locks(inode, &num_fcntl_locks, &num_flock_locks);
unlock_flocks();
flocks = kmalloc((num_fcntl_locks+num_flock_locks) *
sizeof(struct ceph_filelock), GFP_NOFS);
if (!flocks) {
err = -ENOMEM;
goto out_free;
}
lock_flocks();
err = ceph_encode_locks_to_buffer(inode, flocks,
num_fcntl_locks,
num_flock_locks);
unlock_flocks();
if (err) {
kfree(flocks);
if (err == -ENOSPC)
goto encode_again;
goto out_free;
}
/*
* number of encoded locks is stable, so copy to pagelist
*/
rec.v2.flock_len = cpu_to_le32(2*sizeof(u32) +
(num_fcntl_locks+num_flock_locks) *
sizeof(struct ceph_filelock));
err = ceph_pagelist_append(pagelist, &rec, reclen);
if (!err)
err = ceph_locks_to_pagelist(flocks, pagelist,
num_fcntl_locks,
num_flock_locks);
kfree(flocks);
} else {
err = ceph_pagelist_append(pagelist, &rec, reclen);
}
out_free:
kfree(path);
out_dput:

9
fs/ceph/super.h
View File

@ -822,8 +822,13 @@ extern const struct export_operations ceph_export_ops;
extern int ceph_lock(struct file *file, int cmd, struct file_lock *fl);
extern int ceph_flock(struct file *file, int cmd, struct file_lock *fl);
extern void ceph_count_locks(struct inode *inode, int *p_num, int *f_num);
extern int ceph_encode_locks(struct inode *i, struct ceph_pagelist *p,
int p_locks, int f_locks);
extern int ceph_encode_locks_to_buffer(struct inode *inode,
struct ceph_filelock *flocks,
int num_fcntl_locks,
int num_flock_locks);
extern int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
struct ceph_pagelist *pagelist,
int num_fcntl_locks, int num_flock_locks);
extern int lock_to_ceph_filelock(struct file_lock *fl, struct ceph_filelock *c);
/* debugfs.c */