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| author |   Abhi Das <adas@redhat.com> | 2015-12-18 14:11:36 -0600 |
|---|---|---|
| committer |   Al Viro <viro@zeniv.linux.org.uk> | 2016-01-09 02:55:35 -0500 |
| commit | 90330e689c32e5105265c461c54af6ecec3373fa (patch) | |
| tree | 0dcb8a77f49ecc2f5c24fbb74327ccd4323b20d4 /fs/splice.c | |
| parent | fs: xattr: Use kvfree() (diff) | |
| download | linux-dev-90330e689c32e5105265c461c54af6ecec3373fa.tar.xz linux-dev-90330e689c32e5105265c461c54af6ecec3373fa.zip | |
fs: __generic_file_splice_read retry lookup on AOP_TRUNCATED_PAGE
During testing, I discovered that __generic_file_splice_read() returns
0 (EOF) when aops->readpage fails with AOP_TRUNCATED_PAGE on the first
page of a single/multi-page splice read operation. This EOF return code
causes the userspace test to (correctly) report a zero-length read error
when it was expecting otherwise.
The current strategy of returning a partial non-zero read when ->readpage
returns AOP_TRUNCATED_PAGE works only when the failed page is not the
first of the lot being processed.
This patch attempts to retry lookup and call ->readpage again on pages
that had previously failed with AOP_TRUNCATED_PAGE. With this patch, my
tests pass and I haven't noticed any unwanted side effects.
This version removes the thrice-retry loop and instead indefinitely
retries lookups on AOP_TRUNCATED_PAGE errors from ->readpage. This
behavior is now similar to do_generic_file_read().
Signed-off-by: Abhi Das <adas@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/splice.c')
| -rw-r--r-- | fs/splice.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/fs/splice.c b/fs/splice.c index 4cf700d50b40..82bc0d64fc38 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -415,6 +415,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, */ if (!page->mapping) { unlock_page(page); +retry_lookup: page = find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); @@ -439,13 +440,10 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, error = mapping->a_ops->readpage(in, page); if (unlikely(error)) { /* - * We really should re-lookup the page here, - * but it complicates things a lot. Instead - * lets just do what we already stored, and - * we'll get it the next time we are called. + * Re-lookup the page */ if (error == AOP_TRUNCATED_PAGE) - error = 0; + goto retry_lookup; break; } |