From cc6c40e09d7b1c559bdf42f0fe99b16eb7cfc5e3 Mon Sep 17 00:00:00 2001 From: Sergey Bashirov Date: Fri, 3 Oct 2025 12:11:06 +0300 Subject: [PATCH] NFSD/blocklayout: Support multiple extents per LAYOUTGET Allow the pNFS server to respond with multiple extents to a LAYOUTGET request, thereby avoiding unnecessary load on the server and improving performance for the client. The number of LAYOUTGET requests is significantly reduced for various file access patterns, including random and parallel writes. Additionally, this change allows the client to request layouts with the loga_minlength value greater than the minimum possible length of a single extent in XFS. We use this functionality to fix a livelock in the client. Signed-off-by: Sergey Bashirov Reviewed-by: Christoph Hellwig Signed-off-by: Chuck Lever --- fs/nfsd/blocklayout.c | 47 +++++++++++++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 13 deletions(-) diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c index 6d29ea5e86231..101cccbee4a39 100644 --- a/fs/nfsd/blocklayout.c +++ b/fs/nfsd/blocklayout.c @@ -89,9 +89,9 @@ nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode, { struct nfsd4_layout_seg *seg = &args->lg_seg; struct pnfs_block_layout *bl; - struct pnfs_block_extent *bex; - u64 length; - u32 nr_extents_max = 1, block_size = i_blocksize(inode); + struct pnfs_block_extent *first_bex, *last_bex; + u64 offset = seg->offset, length = seg->length; + u32 i, nr_extents_max, block_size = i_blocksize(inode); __be32 nfserr; if (locks_in_grace(SVC_NET(rqstp))) @@ -118,6 +118,13 @@ nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode, PNFS_BLOCK_EXTENT_SIZE) goto out_error; + /* + * Limit the maximum layout size to avoid allocating + * a large buffer on the server for each layout request. + */ + nr_extents_max = (min(args->lg_maxcount, PAGE_SIZE) - + PNFS_BLOCK_LAYOUT4_SIZE) / PNFS_BLOCK_EXTENT_SIZE; + /* * Some clients barf on non-zero block numbers for NONE or INVALID * layouts, so make sure to zero the whole structure. @@ -129,23 +136,37 @@ nfsd4_block_proc_layoutget(struct svc_rqst *rqstp, struct inode *inode, bl->nr_extents = nr_extents_max; args->lg_content = bl; - bex = &bl->extents[0]; - nfserr = nfsd4_block_map_extent(inode, fhp, seg->offset, seg->length, - seg->iomode, args->lg_minlength, bex); - if (nfserr != nfs_ok) - goto out_error; + for (i = 0; i < bl->nr_extents; i++) { + struct pnfs_block_extent *bex = bl->extents + i; + u64 bex_length; + + nfserr = nfsd4_block_map_extent(inode, fhp, offset, length, + seg->iomode, args->lg_minlength, bex); + if (nfserr != nfs_ok) + goto out_error; + + bex_length = bex->len - (offset - bex->foff); + if (bex_length >= length) { + bl->nr_extents = i + 1; + break; + } + + offset = bex->foff + bex->len; + length -= bex_length; + } + + first_bex = bl->extents; + last_bex = bl->extents + bl->nr_extents - 1; nfserr = nfserr_layoutunavailable; - length = bex->foff + bex->len - seg->offset; + length = last_bex->foff + last_bex->len - seg->offset; if (length < args->lg_minlength) { dprintk("pnfsd: extent smaller than minlength\n"); goto out_error; } - seg->offset = bex->foff; - seg->length = bex->len; - - dprintk("GET: 0x%llx:0x%llx %d\n", bex->foff, bex->len, bex->es); + seg->offset = first_bex->foff; + seg->length = last_bex->foff - first_bex->foff + last_bex->len; return nfs_ok; out_error: -- 2.47.3