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authorMitch Harder <mitch.harder@sabayonlinux.org>2012-01-26 15:01:11 -0500
committerChris Mason <chris.mason@oracle.com>2012-01-26 15:01:11 -0500
commit8bedd51b6121c4607784d75f852828d25d119c52 (patch)
treee9299eb7b70a1d2f0ea5a4e23b53c7a6496eea59 /fs
parent6dd70ce4eb7429c2ba6dd9fa46f78a0a2a254038 (diff)
Btrfs: Check for NULL page in extent_range_uptodate
A user has encountered a NULL pointer kernel oops in btrfs when encountering media errors. The problem has been identified as an unhandled NULL pointer returned from find_get_page(). This modification simply checks for a NULL page, and returns with an error if found (the extent_range_uptodate() function returns 1 on errors). After testing this patch, the user reported that the error with the NULL pointer oops was solved. However, there is still a remaining problem with a thread becoming stuck in wait_on_page_locked(page) in the read_extent_buffer_pages(...) function in extent_io.c for (i = start_i; i < num_pages; i++) { page = extent_buffer_page(eb, i); wait_on_page_locked(page); if (!PageUptodate(page)) ret = -EIO; } This patch leaves the issue with the locked page yet to be resolved. Signed-off-by: Mitch Harder <mitch.harder@sabayonlinux.org> Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/extent_io.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 9d09a4f81875..fcf77e1ded40 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3909,6 +3909,8 @@ int extent_range_uptodate(struct extent_io_tree *tree,
while (start <= end) {
index = start >> PAGE_CACHE_SHIFT;
page = find_get_page(tree->mapping, index);
+ if (!page)
+ return 1;
uptodate = PageUptodate(page);
page_cache_release(page);
if (!uptodate) {

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