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| author | Christoph Hellwig <hch@lst.de> | 2014-08-21 11:09:29 -0500 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@primarydata.com> | 2014-09-10 12:47:02 -0700 |
| commit | 921b81a8cd5a4acc2a009778d13eedd377362c4c (patch) | |
| tree | 8efd8cfe55fa1e62de0a557c6d3579e99dc240b9 /fs | |
| parent | be98fd0ac3dd45c1aa404b101caa37f9b317ab57 (diff) | |
| download | lwn-921b81a8cd5a4acc2a009778d13eedd377362c4c.tar.gz lwn-921b81a8cd5a4acc2a009778d13eedd377362c4c.zip | |
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: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/nfs/blocklayout/blocklayout.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c index 5427ae766f06..87a633d03507 100644 --- a/fs/nfs/blocklayout/blocklayout.c +++ b/fs/nfs/blocklayout/blocklayout.c @@ -272,7 +272,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) isect = (sector_t) (f_offset >> SECTOR_SHIFT); /* Code assumes extents are page-aligned */ for (i = pg_index; i < hdr->page_array.npages; i++) { - if (!extent_length) { + if (extent_length <= 0) { /* We've used up the previous extent */ bl_put_extent(be); bl_put_extent(cow_read); @@ -303,6 +303,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) f_offset += pg_len; bytes_left -= pg_len; isect += (pg_offset >> SECTOR_SHIFT); + extent_length -= (pg_offset >> SECTOR_SHIFT); } else { pg_offset = 0; pg_len = PAGE_CACHE_SIZE; @@ -333,7 +334,7 @@ bl_read_pagelist(struct nfs_pgio_header *hdr) } } isect += (pg_len >> SECTOR_SHIFT); - extent_length -= PAGE_CACHE_SECTORS; + extent_length -= (pg_len >> SECTOR_SHIFT); } if ((isect << SECTOR_SHIFT) >= header->inode->i_size) { hdr->res.eof = 1; @@ -797,7 +798,7 @@ next_page: /* Middle pages */ pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT; for (i = pg_index; i < header->page_array.npages; i++) { - if (!extent_length) { + if (extent_length <= 0) { /* We've used up the previous extent */ bl_put_extent(be); bl_put_extent(cow_read); |