On Tue, Oct 27, 2020 at 07:02:55PM +0530, Chandan Babu R wrote: > 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. I /think/ the defer ops will rejoin the buffer each time it rolls, which means that xfs_attr_trans_roll returns with the buffer already joined to the transaction? And I think you're right that the bhold isn't needed, because holding is dictated by the lower levels (i.e. _set_iter). > Please let me know if I am missing something obvious here. The entire function goes away by the end of the series. :) --D > > -- > chandan > > >