diff options
| -rw-r--r-- | fs/iomap/buffered-io.c | 29 | ||||
| -rw-r--r-- | fs/iomap/iter.c | 19 | ||||
| -rw-r--r-- | include/linux/iomap.h | 43 |
3 files changed, 81 insertions, 10 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index dca9ec9dc4a8..356193e44cf0 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -584,7 +584,7 @@ static int iomap_write_begin_inline(const struct iomap_iter *iter, return iomap_read_inline_data(iter, folio); } -static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, +static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, size_t len, struct folio **foliop) { const struct iomap_page_ops *page_ops = iter->iomap.page_ops; @@ -618,6 +618,27 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM; goto out_no_page; } + + /* + * Now we have a locked folio, before we do anything with it we need to + * check that the iomap we have cached is not stale. The inode extent + * mapping can change due to concurrent IO in flight (e.g. + * IOMAP_UNWRITTEN state can change and memory reclaim could have + * reclaimed a previously partially written page at this index after IO + * completion before this write reaches this file offset) and hence we + * could do the wrong thing here (zero a page range incorrectly or fail + * to zero) and corrupt data. + */ + if (page_ops && page_ops->iomap_valid) { + bool iomap_valid = page_ops->iomap_valid(iter->inode, + &iter->iomap); + if (!iomap_valid) { + iter->iomap.flags |= IOMAP_F_STALE; + status = 0; + goto out_unlock; + } + } + if (pos + len > folio_pos(folio) + folio_size(folio)) len = folio_pos(folio) + folio_size(folio) - pos; @@ -773,6 +794,8 @@ again: status = iomap_write_begin(iter, pos, bytes, &folio); if (unlikely(status)) break; + if (iter->iomap.flags & IOMAP_F_STALE) + break; page = folio_file_page(folio, pos >> PAGE_SHIFT); if (mapping_writably_mapped(mapping)) @@ -1081,6 +1104,8 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter) status = iomap_write_begin(iter, pos, bytes, &folio); if (unlikely(status)) return status; + if (iter->iomap.flags & IOMAP_F_STALE) + break; status = iomap_write_end(iter, pos, bytes, bytes, folio); if (WARN_ON_ONCE(status == 0)) @@ -1136,6 +1161,8 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero) status = iomap_write_begin(iter, pos, bytes, &folio); if (status) return status; + if (iter->iomap.flags & IOMAP_F_STALE) + break; offset = offset_in_folio(folio, pos); if (bytes > folio_size(folio) - offset) diff --git a/fs/iomap/iter.c b/fs/iomap/iter.c index a1c7592d2ade..79a0614eaab7 100644 --- a/fs/iomap/iter.c +++ b/fs/iomap/iter.c @@ -7,12 +7,28 @@ #include <linux/iomap.h> #include "trace.h" +/* + * Advance to the next range we need to map. + * + * If the iomap is marked IOMAP_F_STALE, it means the existing map was not fully + * processed - it was aborted because the extent the iomap spanned may have been + * changed during the operation. In this case, the iteration behaviour is to + * remap the unprocessed range of the iter, and that means we may need to remap + * even when we've made no progress (i.e. iter->processed = 0). Hence the + * "finished iterating" case needs to distinguish between + * (processed = 0) meaning we are done and (processed = 0 && stale) meaning we + * need to remap the entire remaining range. + */ static inline int iomap_iter_advance(struct iomap_iter *iter) { + bool stale = iter->iomap.flags & IOMAP_F_STALE; + /* handle the previous iteration (if any) */ if (iter->iomap.length) { - if (iter->processed <= 0) + if (iter->processed < 0) return iter->processed; + if (!iter->processed && !stale) + return 0; if (WARN_ON_ONCE(iter->processed > iomap_length(iter))) return -EIO; iter->pos += iter->processed; @@ -33,6 +49,7 @@ static inline void iomap_iter_done(struct iomap_iter *iter) WARN_ON_ONCE(iter->iomap.offset > iter->pos); WARN_ON_ONCE(iter->iomap.length == 0); WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos); + WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE); trace_iomap_iter_dstmap(iter->inode, &iter->iomap); if (iter->srcmap.type != IOMAP_HOLE) diff --git a/include/linux/iomap.h b/include/linux/iomap.h index 0698c4b8ce0e..0983dfc9a203 100644 --- a/include/linux/iomap.h +++ b/include/linux/iomap.h @@ -49,26 +49,35 @@ struct vm_fault; * * IOMAP_F_BUFFER_HEAD indicates that the file system requires the use of * buffer heads for this mapping. + * + * IOMAP_F_XATTR indicates that the iomap is for an extended attribute extent + * rather than a file data extent. */ -#define IOMAP_F_NEW 0x01 -#define IOMAP_F_DIRTY 0x02 -#define IOMAP_F_SHARED 0x04 -#define IOMAP_F_MERGED 0x08 -#define IOMAP_F_BUFFER_HEAD 0x10 -#define IOMAP_F_ZONE_APPEND 0x20 +#define IOMAP_F_NEW (1U << 0) +#define IOMAP_F_DIRTY (1U << 1) +#define IOMAP_F_SHARED (1U << 2) +#define IOMAP_F_MERGED (1U << 3) +#define IOMAP_F_BUFFER_HEAD (1U << 4) +#define IOMAP_F_ZONE_APPEND (1U << 5) +#define IOMAP_F_XATTR (1U << 6) /* * Flags set by the core iomap code during operations: * * IOMAP_F_SIZE_CHANGED indicates to the iomap_end method that the file size * has changed as the result of this write operation. + * + * IOMAP_F_STALE indicates that the iomap is not valid any longer and the file + * range it covers needs to be remapped by the high level before the operation + * can proceed. */ -#define IOMAP_F_SIZE_CHANGED 0x100 +#define IOMAP_F_SIZE_CHANGED (1U << 8) +#define IOMAP_F_STALE (1U << 9) /* * Flags from 0x1000 up are for file system specific usage: */ -#define IOMAP_F_PRIVATE 0x1000 +#define IOMAP_F_PRIVATE (1U << 12) /* @@ -89,6 +98,7 @@ struct iomap { void *inline_data; void *private; /* filesystem private */ const struct iomap_page_ops *page_ops; + u64 validity_cookie; /* used with .iomap_valid() */ }; static inline sector_t iomap_sector(const struct iomap *iomap, loff_t pos) @@ -128,6 +138,23 @@ struct iomap_page_ops { int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len); void (*page_done)(struct inode *inode, loff_t pos, unsigned copied, struct page *page); + + /* + * Check that the cached iomap still maps correctly to the filesystem's + * internal extent map. FS internal extent maps can change while iomap + * is iterating a cached iomap, so this hook allows iomap to detect that + * the iomap needs to be refreshed during a long running write + * operation. + * + * The filesystem can store internal state (e.g. a sequence number) in + * iomap->validity_cookie when the iomap is first mapped to be able to + * detect changes between mapping time and whenever .iomap_valid() is + * called. + * + * This is called with the folio over the specified file position held + * locked by the iomap code. + */ + bool (*iomap_valid)(struct inode *inode, const struct iomap *iomap); }; /* |