kernel.git/fs/nfs/read.c, branch linux-6.10.y

nfs: pass explicit offset/count to trace events

2024-08-03T07:00:05Z

[ Upstream commit fada32ed6dbc748f447c8d050a961b75d946055a ] nfs_folio_length is unsafe to use without having the folio locked and a check for a NULL ->f_mapping that protects against truncations and can lead to kernel crashes. E.g. when running xfstests generic/065 with all nfs trace points enabled. Follow the model of the XFS trace points and pass in an explіcit offset and length. This has the additional benefit that these values can be more accurate as some of the users touch partial folio ranges. Fixes: eb5654b3b89d ("NFS: Enable tracing of nfs_invalidate_folio() and nfs_launder_folio()") Reported-by: Chuck Lever Signed-off-by: Christoph Hellwig Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

NFS: Read unlock folio on nfs_page_create_from_folio() error

2024-03-09T14:14:51Z

The netfs conversion lost a folio_unlock() for the case where nfs_page_create_from_folio() returns an error (usually -ENOMEM). Restore it. Reported-by: David Jeffery Cc: # 6.4+ Fixes: 000dbe0bec05 ("NFS: Convert buffered read paths to use netfs when fscache is enabled") Signed-off-by: Benjamin Coddington Acked-by: Dave Wysochanski Signed-off-by: Trond Myklebust

NFSv4.2: Rework scratch handling for READ_PLUS (again)

2023-08-23T19:58:47Z

I found that the read code might send multiple requests using the same nfs_pgio_header, but nfs4_proc_read_setup() is only called once. This is how we ended up occasionally double-freeing the scratch buffer, but also means we set a NULL pointer but non-zero length to the xdr scratch buffer. This results in an oops the first time decoding needs to copy something to scratch, which frequently happens when decoding READ_PLUS hole segments. I fix this by moving scratch handling into the pageio read code. I provide a function to allocate scratch space for decoding read replies, and free the scratch buffer when the nfs_pgio_header is freed. Fixes: fbd2a05f29a9 (NFSv4.2: Rework scratch handling for READ_PLUS) Signed-off-by: Anna Schumaker

NFS: Convert buffered read paths to use netfs when fscache is enabled

2023-04-11T17:08:26Z

Convert the NFS buffered read code paths to corresponding netfs APIs, but only when fscache is configured and enabled. The netfs API defines struct netfs_request_ops which must be filled in by the network filesystem. For NFS, we only need to define 5 of the functions, the main one being the issue_read() function. The issue_read() function is called by the netfs layer when a read cannot be fulfilled locally, and must be sent to the server (either the cache is not active, or it is active but the data is not available). Once the read from the server is complete, netfs requires a call to netfs_subreq_terminated() which conveys either how many bytes were read successfully, or an error. Note that issue_read() is called with a structure, netfs_io_subrequest, which defines the IO requested, and contains a start and a length (both in bytes), and assumes the underlying netfs will return a either an error on the whole region, or the number of bytes successfully read. The NFS IO path is page based and the main APIs are the pgio APIs defined in pagelist.c. For the pgio APIs, there is no way for the caller to know how many RPCs will be sent and how the pages will be broken up into underlying RPCs, each of which will have their own completion and return code. In contrast, netfs is subrequest based, a single subrequest may contain multiple pages, and a single subrequest is initiated with issue_read() and terminated with netfs_subreq_terminated(). Thus, to utilze the netfs APIs, NFS needs some way to accommodate the netfs API requirement on the single response to the whole subrequest, while also minimizing disruptive changes to the NFS pgio layer. The approach taken with this patch is to allocate a small structure for each nfs_netfs_issue_read() call, store the final error and number of bytes successfully transferred in the structure, and update these values as each RPC completes. The refcount on the structure is used as a marker for the last RPC completion, is incremented in nfs_netfs_read_initiate(), and decremented inside nfs_netfs_read_completion(), when a nfs_pgio_header contains a valid pointer to the data. On the final put (which signals the final outstanding RPC is complete) in nfs_netfs_read_completion(), call netfs_subreq_terminated() with either the final error value (if one or more READs complete with an error) or the number of bytes successfully transferred (if all RPCs complete successfully). Note that when all RPCs complete successfully, the number of bytes transferred is capped to the length of the subrequest. Capping the transferred length to the subrequest length prevents "Subreq overread" warnings from netfs. This is due to the "aligned_len" in nfs_pageio_add_page(), and the corner case where NFS requests a full page at the end of the file, even when i_size reflects only a partial page (NFS overread). Signed-off-by: Dave Wysochanski Tested-by: Daire Byrne Signed-off-by: Anna Schumaker

NFS: Rename readpage_async_filler to nfs_read_add_folio

2023-04-11T16:59:23Z

Rename readpage_async_filler to nfs_read_add_folio to better reflect what this function does (add a folio to the nfs_pageio_descriptor), and simplify arguments to this function by removing struct nfs_readdesc. Signed-off-by: Dave Wysochanski Tested-by: Daire Byrne Signed-off-by: Anna Schumaker

NFS: Fix /proc/PID/io read_bytes for buffered reads

2023-03-14T17:47:43Z

Prior to commit 8786fde8421c ("Convert NFS from readpages to readahead"), nfs_readpages() used the old mm interface read_cache_pages() which called task_io_account_read() for each NFS page read. After this commit, nfs_readpages() is converted to nfs_readahead(), which now uses the new mm interface readahead_page(). The new interface requires callers to call task_io_account_read() themselves. In addition, to nfs_readahead() task_io_account_read() should also be called from nfs_read_folio(). Fixes: 8786fde8421c ("Convert NFS from readpages to readahead") Link: https://lore.kernel.org/linux-nfs/CAPt2mGNEYUk5u8V4abe=5MM5msZqmvzCVrtCP4Qw1n=gCHCnww@mail.gmail.com/ Signed-off-by: Dave Wysochanski Signed-off-by: Anna Schumaker

NFS: Remove unnecessary check in nfs_read_folio()

2023-02-14T19:22:33Z

All the callers are expected to supply a valid struct file argument, so there is no need for the NULL check. Reported-by: kernel test robot Reported-by: Dan Carpenter Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

NFS: Convert buffered reads to use folios

2023-02-14T19:22:32Z

Perform a largely mechanical conversion of references to struct page and page-specific functions to use the folio equivalents. Note that the fscache functionality remains untouched. Instead we just pass in the folio page. This should be OK, as long as we use order 0 folios together with fscache. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

nfs: Leave pages in the pagecache if readpage failed

2022-06-29T12:51:07Z

The pagecache handles readpage failing by itself; it doesn't want filesystems to remove pages from under it. Signed-off-by: Matthew Wilcox (Oracle)

nfs: Convert nfs to read_folio

2022-05-09T20:21:46Z

This is a "weak" conversion which converts straight back to using pages. A full conversion should be performed at some point, hopefully by someone familiar with the filesystem. Signed-off-by: Matthew Wilcox (Oracle)