On Friday 23 October 2020 12:04:28 PM IST Allison Henderson wrote: > This patch modifies the attr set routines to be delay ready. This means > they no longer roll or commit transactions, but instead return -EAGAIN > to have the calling routine roll and refresh the transaction. In this > series, xfs_attr_set_args has become xfs_attr_set_iter, which uses a > state machine like switch to keep track of where it was when EAGAIN was > returned. See xfs_attr.h for a more detailed diagram of the states. > > Two new helper functions have been added: xfs_attr_rmtval_set_init and > xfs_attr_rmtval_set_blk. They provide a subset of logic similar to > xfs_attr_rmtval_set, but they store the current block in the delay attr > context to allow the caller to roll the transaction between allocations. > This helps to simplify and consolidate code used by > xfs_attr_leaf_addname and xfs_attr_node_addname. xfs_attr_set_args has > now become a simple loop to refresh the transaction until the operation > is completed. Lastly, xfs_attr_rmtval_remove is no longer used, and is > removed. One nit. xfs_attr_rmtval_remove()'s prototype declaration needs to be removed from xfs_attr_remote.h. > > Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx> > --- > fs/xfs/libxfs/xfs_attr.c | 370 ++++++++++++++++++++++++++-------------- > fs/xfs/libxfs/xfs_attr.h | 126 +++++++++++++- > fs/xfs/libxfs/xfs_attr_remote.c | 99 +++++++---- > fs/xfs/libxfs/xfs_attr_remote.h | 4 + > fs/xfs/xfs_trace.h | 1 - > 5 files changed, 439 insertions(+), 161 deletions(-) > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c > index 6ca94cb..95c98d7 100644 > --- a/fs/xfs/libxfs/xfs_attr.c > +++ b/fs/xfs/libxfs/xfs_attr.c > @@ -44,7 +44,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args); > * Internal routines when attribute list is one block. > */ > STATIC int xfs_attr_leaf_get(xfs_da_args_t *args); > -STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args); > +STATIC int xfs_attr_leaf_addname(struct xfs_delattr_context *dac); > STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args); > STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp); > > @@ -52,12 +52,15 @@ STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp); > * Internal routines when attribute list is more than one block. > */ > STATIC int xfs_attr_node_get(xfs_da_args_t *args); > -STATIC int xfs_attr_node_addname(xfs_da_args_t *args); > +STATIC int xfs_attr_node_addname(struct xfs_delattr_context *dac); > STATIC int xfs_attr_node_removename_iter(struct xfs_delattr_context *dac); > STATIC int xfs_attr_node_hasname(xfs_da_args_t *args, > struct xfs_da_state **state); > STATIC int xfs_attr_fillstate(xfs_da_state_t *state); > STATIC int xfs_attr_refillstate(xfs_da_state_t *state); > +STATIC int xfs_attr_leaf_try_add(struct xfs_da_args *args, struct xfs_buf *bp); > +STATIC int xfs_attr_set_iter(struct xfs_delattr_context *dac, > + struct xfs_buf **leaf_bp); > > int > xfs_inode_hasattr( > @@ -218,8 +221,11 @@ xfs_attr_is_shortform( > > /* > * Attempts to set an attr in shortform, or converts short form to leaf form if > - * there is not enough room. If the attr is set, the transaction is committed > - * and set to NULL. > + * there is not enough room. This function is meant to operate as a helper > + * routine to the delayed attribute functions. It returns -EAGAIN to indicate > + * that the calling function should roll the transaction, and then proceed to > + * add the attr in leaf form. This subroutine does not expect to be recalled > + * again like the other delayed attr routines do. > */ > STATIC int > xfs_attr_set_shortform( > @@ -227,16 +233,16 @@ xfs_attr_set_shortform( > struct xfs_buf **leaf_bp) > { > struct xfs_inode *dp = args->dp; > - int error, error2 = 0; > + int error = 0; > > /* > * Try to add the attr to the attribute list in the inode. > */ > error = xfs_attr_try_sf_addname(dp, args); > + > + /* Should only be 0, -EEXIST or ENOSPC */ > if (error != -ENOSPC) { > - error2 = xfs_trans_commit(args->trans); > - args->trans = NULL; > - return error ? error : error2; > + return error; > } > /* > * It won't fit in the shortform, transform to a leaf block. GROT: > @@ -249,18 +255,10 @@ xfs_attr_set_shortform( > /* > * Prevent the leaf buffer from being unlocked so that a concurrent AIL > * push cannot grab the half-baked leaf buffer and run into problems > - * with the write verifier. Once we're done rolling the transaction we > - * can release the hold and add the attr to the leaf. > + * with the write verifier. > */ > xfs_trans_bhold(args->trans, *leaf_bp); > - error = xfs_defer_finish(&args->trans); > - xfs_trans_bhold_release(args->trans, *leaf_bp); > - if (error) { > - xfs_trans_brelse(args->trans, *leaf_bp); > - return error; > - } > - > - return 0; > + return -EAGAIN; > } > > /* > @@ -268,7 +266,7 @@ xfs_attr_set_shortform( > * also checks for a defer finish. Transaction is finished and rolled as > * needed, and returns true of false if the delayed operation should continue. > */ > -int > +STATIC int > xfs_attr_trans_roll( > struct xfs_delattr_context *dac) > { > @@ -297,61 +295,130 @@ int > xfs_attr_set_args( > struct xfs_da_args *args) > { > - struct xfs_inode *dp = args->dp; > - struct xfs_buf *leaf_bp = NULL; > - int error = 0; > + struct xfs_buf *leaf_bp = NULL; > + int error = 0; > + struct xfs_delattr_context dac = { > + .da_args = args, > + }; > + > + do { > + error = xfs_attr_set_iter(&dac, &leaf_bp); > + if (error != -EAGAIN) > + break; > + > + error = xfs_attr_trans_roll(&dac); > + if (error) > + return error; > + > + if (leaf_bp) { > + xfs_trans_bjoin(args->trans, leaf_bp); > + xfs_trans_bhold(args->trans, leaf_bp); > + } When xfs_attr_set_iter() causes a "short form" attribute list to be converted to "leaf form", leaf_bp would point to an xfs_buf which has been added to the transaction and also XFS_BLI_HOLD flag is set on the buffer (last statement in xfs_attr_set_shortform()). XFS_BLI_HOLD flag makes sure that the new transaction allocated by xfs_attr_trans_roll() would continue to have leaf_bp in the transaction's item list. Hence I think the above calls to xfs_trans_bjoin() and xfs_trans_bhold() are not required. Please let me know if I am missing something obvious here. -- chandan