Commit 921b81a8 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Trond Myklebust

pnfs/blocklayout: correctly decrement extent length

When we do non-page sized reads we can underflow the extent_length variable
and read incorrect data.  Fix the extent_length calculation and change to
defensive <= checks for the extent length in the read and write path.
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent be98fd0a
...@@ -272,7 +272,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) ...@@ -272,7 +272,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
isect = (sector_t) (f_offset >> SECTOR_SHIFT); isect = (sector_t) (f_offset >> SECTOR_SHIFT);
/* Code assumes extents are page-aligned */ /* Code assumes extents are page-aligned */
for (i = pg_index; i < hdr->page_array.npages; i++) { for (i = pg_index; i < hdr->page_array.npages; i++) {
if (!extent_length) { if (extent_length <= 0) {
/* We've used up the previous extent */ /* We've used up the previous extent */
bl_put_extent(be); bl_put_extent(be);
bl_put_extent(cow_read); bl_put_extent(cow_read);
...@@ -303,6 +303,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) ...@@ -303,6 +303,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
f_offset += pg_len; f_offset += pg_len;
bytes_left -= pg_len; bytes_left -= pg_len;
isect += (pg_offset >> SECTOR_SHIFT); isect += (pg_offset >> SECTOR_SHIFT);
extent_length -= (pg_offset >> SECTOR_SHIFT);
} else { } else {
pg_offset = 0; pg_offset = 0;
pg_len = PAGE_CACHE_SIZE; pg_len = PAGE_CACHE_SIZE;
...@@ -333,7 +334,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) ...@@ -333,7 +334,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
} }
} }
isect += (pg_len >> SECTOR_SHIFT); isect += (pg_len >> SECTOR_SHIFT);
extent_length -= PAGE_CACHE_SECTORS; extent_length -= (pg_len >> SECTOR_SHIFT);
} }
if ((isect << SECTOR_SHIFT) >= header->inode->i_size) { if ((isect << SECTOR_SHIFT) >= header->inode->i_size) {
hdr->res.eof = 1; hdr->res.eof = 1;
...@@ -797,7 +798,7 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync) ...@@ -797,7 +798,7 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
/* Middle pages */ /* Middle pages */
pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT; pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
for (i = pg_index; i < header->page_array.npages; i++) { for (i = pg_index; i < header->page_array.npages; i++) {
if (!extent_length) { if (extent_length <= 0) {
/* We've used up the previous extent */ /* We've used up the previous extent */
bl_put_extent(be); bl_put_extent(be);
bl_put_extent(cow_read); bl_put_extent(cow_read);
......
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