From: Fan Yong <fan.y...@intel.com> There is race condition when allocating fid/seq in parallel as following:
The thread1 will release the lcs_mutex via seq_fid_alloc_prep(), then another fid allocation thread2 can obtain the lcs_mutex and allocate FID in the new sequence that has just been allocated by the thread1 via seq_client_alloc_seq(); and then after thread2 released the lcs_mutex, the thread1 will re-allocate the current FID in the new sequence without checking whether some others have already taken such FID in the new sequence during it re-obtaining the lcs_mutex. Such race will cause two objects to use the same FID, and trigger OI conflict and LMA verification failures. This patch makes the fid allocation and lu_client_seq modification to be protected by the lcs_mutex. Signed-off-by: Fan Yong <fan.y...@intel.com> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8319 Reviewed-on: http://review.whamcloud.com/20939 Reviewed-by: Alex Zhuravlev <alexey.zhurav...@intel.com> Reviewed-by: Andreas Dilger <andreas.dil...@intel.com> Signed-off-by: James Simmons <jsimm...@infradead.org> --- drivers/staging/lustre/lustre/fid/fid_request.c | 55 ++++++++++++++++--------- 1 file changed, 35 insertions(+), 20 deletions(-) diff --git a/drivers/staging/lustre/lustre/fid/fid_request.c b/drivers/staging/lustre/lustre/fid/fid_request.c index 999f250..62a9f7e 100644 --- a/drivers/staging/lustre/lustre/fid/fid_request.c +++ b/drivers/staging/lustre/lustre/fid/fid_request.c @@ -211,12 +211,35 @@ static int seq_fid_alloc_prep(struct lu_client_seq *seq, return 0; } -static void seq_fid_alloc_fini(struct lu_client_seq *seq) +static void seq_fid_alloc_fini(struct lu_client_seq *seq, u64 seqnr, + bool whole) { LASSERT(seq->lcs_update == 1); + mutex_lock(&seq->lcs_mutex); + if (seqnr != 0) { + CDEBUG(D_INFO, "%s: New sequence [0x%16.16llx]\n", + seq->lcs_name, seqnr); + + seq->lcs_fid.f_seq = seqnr; + if (whole) { + /* + * Since the caller require the whole seq, + * so marked this seq to be used + */ + if (seq->lcs_type == LUSTRE_SEQ_METADATA) + seq->lcs_fid.f_oid = + LUSTRE_METADATA_SEQ_MAX_WIDTH; + else + seq->lcs_fid.f_oid = LUSTRE_DATA_SEQ_MAX_WIDTH; + } else { + seq->lcs_fid.f_oid = LUSTRE_FID_INIT_OID; + } + seq->lcs_fid.f_ver = 0; + } + --seq->lcs_update; - wake_up(&seq->lcs_waitq); + wake_up_all(&seq->lcs_waitq); } /* Allocate new fid on passed client @seq and save it to @fid. */ @@ -238,41 +261,33 @@ int seq_client_alloc_fid(const struct lu_env *env, while (1) { u64 seqnr; - if (!fid_is_zero(&seq->lcs_fid) && - fid_oid(&seq->lcs_fid) < seq->lcs_width) { + if (unlikely(!fid_is_zero(&seq->lcs_fid) && + fid_oid(&seq->lcs_fid) < seq->lcs_width)) { /* Just bump last allocated fid and return to caller. */ - seq->lcs_fid.f_oid += 1; + seq->lcs_fid.f_oid++; rc = 0; break; } + /* + * Release seq::lcs_mutex via seq_fid_alloc_prep() to avoid + * deadlock during seq_client_alloc_seq(). + */ rc = seq_fid_alloc_prep(seq, &link); if (rc) continue; rc = seq_client_alloc_seq(env, seq, &seqnr); + /* Re-take seq::lcs_mutex via seq_fid_alloc_fini(). */ + seq_fid_alloc_fini(seq, rc ? 0 : seqnr, false); if (rc) { - CERROR("%s: Can't allocate new sequence, rc %d\n", + CERROR("%s: Can't allocate new sequence, rc = %d\n", seq->lcs_name, rc); - seq_fid_alloc_fini(seq); mutex_unlock(&seq->lcs_mutex); return rc; } - CDEBUG(D_INFO, "%s: Switch to sequence [0x%16.16Lx]\n", - seq->lcs_name, seqnr); - - seq->lcs_fid.f_oid = LUSTRE_FID_INIT_OID; - seq->lcs_fid.f_seq = seqnr; - seq->lcs_fid.f_ver = 0; - - /* - * Inform caller that sequence switch is performed to allow it - * to setup FLD for it. - */ rc = 1; - - seq_fid_alloc_fini(seq); break; } -- 1.8.3.1 _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
