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NFS: Fix an ABBA spinlock issue in pnfs_update_layout() 

We need to drop the inode spinlock while calling nfs4_select_rw_stateid(),
since nfs4_copy_delegation_stateid() could take the delegation lock.
Note that it is safe to do this, since all other calls to
pnfs_update_layout() for that inode will find themselves blocked by
the lock we hold on NFS_LAYOUT_FIRST_LAYOUTGET.

Fixes: fc51b1cf39 ("NFS: Beware when dereferencing the delegation cred")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-04-13 15:55:21 -04:00
parent 8f3d9f3542
commit fbf4bcc9a8
1 changed files with 2 additions and 1 deletions
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3
fs/nfs/pnfs.c
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@ -2023,6 +2023,7 @@ pnfs_update_layout(struct inode *ino,
goto lookup_again;
}
spin_unlock(&ino->i_lock);
first = true;
status = nfs4_select_rw_stateid(ctx->state,
iomode == IOMODE_RW ? FMODE_WRITE : FMODE_READ,
@ -2032,12 +2033,12 @@ pnfs_update_layout(struct inode *ino,
trace_pnfs_update_layout(ino, pos, count,
iomode, lo, lseg,
PNFS_UPDATE_LAYOUT_INVALID_OPEN);
spin_unlock(&ino->i_lock);
nfs4_schedule_stateid_recovery(server, ctx->state);
pnfs_clear_first_layoutget(lo);
pnfs_put_layout_hdr(lo);
goto lookup_again;
}
spin_lock(&ino->i_lock);
} else {
nfs4_stateid_copy(&stateid, &lo->plh_stateid);
}