6.10-stable review patch. If anyone has any objections, please let me know.
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From: David Howells dhowells@redhat.com
[ Upstream commit cce6bfa6ca0e30af9927b0074c97fe6a92f28092 ]
When netfslib writes to a folio that it doesn't have data for, but that data exists on the server, it will make a 'streaming write' whereby it stores data in a folio that is marked dirty, but not uptodate. When it does this, it attaches a record to folio->private to track the dirty region.
When truncate() or fallocate() wants to invalidate part of such a folio, it will call into ->invalidate_folio(), specifying the part of the folio that is to be invalidated. netfs_invalidate_folio(), on behalf of the filesystem, must then determine how to trim the streaming write record. In a couple of cases, however, it does this incorrectly (the reduce-length and move-start cases are switched over and don't, in any case, calculate the value correctly).
Fix this by making the logic tree more obvious and fixing the cases.
Fixes: 9ebff83e6481 ("netfs: Prep to use folio->private for write grouping and streaming write") Signed-off-by: David Howells dhowells@redhat.com Link: https://lore.kernel.org/r/20240823200819.532106-5-dhowells@redhat.com cc: Matthew Wilcox (Oracle) willy@infradead.org cc: Pankaj Raghav p.raghav@samsung.com cc: Jeff Layton jlayton@kernel.org cc: Marc Dionne marc.dionne@auristor.com cc: linux-afs@lists.infradead.org cc: netfs@lists.linux.dev cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/netfs/misc.c | 50 ++++++++++++++++++++++++++++++++++--------------- 1 file changed, 35 insertions(+), 15 deletions(-)
diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 21acf4b092a46..a46bf569303fc 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -97,10 +97,20 @@ EXPORT_SYMBOL(netfs_clear_inode_writeback); void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) { struct netfs_folio *finfo; + struct netfs_inode *ctx = netfs_inode(folio_inode(folio)); size_t flen = folio_size(folio);
kenter("{%lx},%zx,%zx", folio->index, offset, length);
+ if (offset == 0 && length == flen) { + unsigned long long i_size = i_size_read(&ctx->inode); + unsigned long long fpos = folio_pos(folio), end; + + end = umin(fpos + flen, i_size); + if (fpos < i_size && end > ctx->zero_point) + ctx->zero_point = end; + } + folio_wait_private_2(folio); /* [DEPRECATED] */
if (!folio_test_private(folio)) @@ -115,18 +125,34 @@ void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) /* We have a partially uptodate page from a streaming write. */ unsigned int fstart = finfo->dirty_offset; unsigned int fend = fstart + finfo->dirty_len; - unsigned int end = offset + length; + unsigned int iend = offset + length;
if (offset >= fend) return; - if (end <= fstart) + if (iend <= fstart) + return; + + /* The invalidation region overlaps the data. If the region + * covers the start of the data, we either move along the start + * or just erase the data entirely. + */ + if (offset <= fstart) { + if (iend >= fend) + goto erase_completely; + /* Move the start of the data. */ + finfo->dirty_len = fend - iend; + finfo->dirty_offset = offset; + return; + } + + /* Reduce the length of the data if the invalidation region + * covers the tail part. + */ + if (iend >= fend) { + finfo->dirty_len = offset - fstart; return; - if (offset <= fstart && end >= fend) - goto erase_completely; - if (offset <= fstart && end > fstart) - goto reduce_len; - if (offset > fstart && end >= fend) - goto move_start; + } + /* A partial write was split. The caller has already zeroed * it, so just absorb the hole. */ @@ -139,12 +165,6 @@ void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) folio_clear_uptodate(folio); kfree(finfo); return; -reduce_len: - finfo->dirty_len = offset + length - finfo->dirty_offset; - return; -move_start: - finfo->dirty_len -= offset - finfo->dirty_offset; - finfo->dirty_offset = offset; } EXPORT_SYMBOL(netfs_invalidate_folio);
@@ -164,7 +184,7 @@ bool netfs_release_folio(struct folio *folio, gfp_t gfp) if (folio_test_dirty(folio)) return false;
- end = folio_pos(folio) + folio_size(folio); + end = umin(folio_pos(folio) + folio_size(folio), i_size_read(&ctx->inode)); if (end > ctx->zero_point) ctx->zero_point = end;