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xfs: fix EFI recovery livelocks

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This series fixes a customer-reported transaction reservation bug
 introduced ten years ago that could result in livelocks during log
 recovery.  Log intent item recovery single-steps each step of a deferred
 op chain, which means that each step only needs to allocate one
 transaction's worth of space in the log, not an entire chain all at
 once.  This single-stepping is critical to unpinning the log tail since
 there's nobody else to do it for us.
 
 This has been lightly tested with fstests.  Enjoy!
 
 Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Merge tag 'fix-efi-recovery-6.6_2023-09-12' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-6.6-fixesA

xfs: fix EFI recovery livelocks

This series fixes a customer-reported transaction reservation bug
introduced ten years ago that could result in livelocks during log
recovery.  Log intent item recovery single-steps each step of a deferred
op chain, which means that each step only needs to allocate one
transaction's worth of space in the log, not an entire chain all at
once.  This single-stepping is critical to unpinning the log tail since
there's nobody else to do it for us.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

* tag 'fix-efi-recovery-6.6_2023-09-12' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
  xfs: reserve less log space when recovering log intent items
This commit is contained in:
Chandan Babu R 2023-09-13 10:22:26 +05:30
commit b6c2b6378d
6 changed files with 40 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
fs/xfs/libxfs/xfs_log_recover.h
View File

@ -131,4 +131,26 @@ void xlog_check_buf_cancel_table(struct xlog *log);
#define xlog_check_buf_cancel_table(log) do { } while (0)
#endif
/*
* Transform a regular reservation into one suitable for recovery of a log
* intent item.
*
* Intent recovery only runs a single step of the transaction chain and defers
* the rest to a separate transaction. Therefore, we reduce logcount to 1 here
* to avoid livelocks if the log grant space is nearly exhausted due to the
* recovered intent pinning the tail. Keep the same logflags to avoid tripping
* asserts elsewhere. Struct copies abound below.
*/
static inline struct xfs_trans_res
xlog_recover_resv(const struct xfs_trans_res *r)
{
struct xfs_trans_res ret = {
.tr_logres = r->tr_logres,
.tr_logcount = 1,
.tr_logflags = r->tr_logflags,
};
return ret;
}
#endif /* __XFS_LOG_RECOVER_H__ */

7
fs/xfs/xfs_attr_item.c
View File

@ -547,7 +547,7 @@ xfs_attri_item_recover(
struct xfs_inode *ip;
struct xfs_da_args *args;
struct xfs_trans *tp;
struct xfs_trans_res tres;
struct xfs_trans_res resv;
struct xfs_attri_log_format *attrp;
struct xfs_attri_log_nameval *nv = attrip->attri_nameval;
int error;
@ -618,8 +618,9 @@ xfs_attri_item_recover(
goto out;
}
xfs_init_attr_trans(args, &tres, &total);
error = xfs_trans_alloc(mp, &tres, total, 0, XFS_TRANS_RESERVE, &tp);
xfs_init_attr_trans(args, &resv, &total);
resv = xlog_recover_resv(&resv);
error = xfs_trans_alloc(mp, &resv, total, 0, XFS_TRANS_RESERVE, &tp);
if (error)
goto out;

4
fs/xfs/xfs_bmap_item.c
View File

@ -490,6 +490,7 @@ xfs_bui_item_recover(
struct list_head *capture_list)
{
struct xfs_bmap_intent fake = { };
struct xfs_trans_res resv;
struct xfs_bui_log_item *buip = BUI_ITEM(lip);
struct xfs_trans *tp;
struct xfs_inode *ip = NULL;
@ -515,7 +516,8 @@ xfs_bui_item_recover(
return error;
/* Allocate transaction and do the work. */
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
resv = xlog_recover_resv(&M_RES(mp)->tr_itruncate);
error = xfs_trans_alloc(mp, &resv,
XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK), 0, 0, &tp);
if (error)
goto err_rele;

4
fs/xfs/xfs_extfree_item.c
View File

@ -660,6 +660,7 @@ xfs_efi_item_recover(
struct xfs_log_item *lip,
struct list_head *capture_list)
{
struct xfs_trans_res resv;
struct xfs_efi_log_item *efip = EFI_ITEM(lip);
struct xfs_mount *mp = lip->li_log->l_mp;
struct xfs_efd_log_item *efdp;
@ -683,7 +684,8 @@ xfs_efi_item_recover(
}
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
resv = xlog_recover_resv(&M_RES(mp)->tr_itruncate);
error = xfs_trans_alloc(mp, &resv, 0, 0, 0, &tp);
if (error)
return error;
efdp = xfs_trans_get_efd(tp, efip, efip->efi_format.efi_nextents);

6
fs/xfs/xfs_refcount_item.c
View File

@ -477,6 +477,7 @@ xfs_cui_item_recover(
struct xfs_log_item *lip,
struct list_head *capture_list)
{
struct xfs_trans_res resv;
struct xfs_cui_log_item *cuip = CUI_ITEM(lip);
struct xfs_cud_log_item *cudp;
struct xfs_trans *tp;
@ -514,8 +515,9 @@ xfs_cui_item_recover(
* doesn't fit. We need to reserve enough blocks to handle a
* full btree split on either end of the refcount range.
*/
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
mp->m_refc_maxlevels * 2, 0, XFS_TRANS_RESERVE, &tp);
resv = xlog_recover_resv(&M_RES(mp)->tr_itruncate);
error = xfs_trans_alloc(mp, &resv, mp->m_refc_maxlevels * 2, 0,
XFS_TRANS_RESERVE, &tp);
if (error)
return error;

6
fs/xfs/xfs_rmap_item.c
View File

@ -507,6 +507,7 @@ xfs_rui_item_recover(
struct xfs_log_item *lip,
struct list_head *capture_list)
{
struct xfs_trans_res resv;
struct xfs_rui_log_item *ruip = RUI_ITEM(lip);
struct xfs_rud_log_item *rudp;
struct xfs_trans *tp;
@ -530,8 +531,9 @@ xfs_rui_item_recover(
}
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate,
mp->m_rmap_maxlevels, 0, XFS_TRANS_RESERVE, &tp);
resv = xlog_recover_resv(&M_RES(mp)->tr_itruncate);
error = xfs_trans_alloc(mp, &resv, mp->m_rmap_maxlevels, 0,
XFS_TRANS_RESERVE, &tp);
if (error)
return error;
rudp = xfs_trans_get_rud(tp, ruip);